Looking for the cloud-hosted version? Comfy Cloud MCP is set up below — install it instead of this server, or alongside it.

What it does:

• 🖼️ Generate — run a workflow JSON (API-format or UI export), or go text-prompt → image in one call.
• ⏱️ Monitor jobs — submit async, then wait / watch / cancel, read the failure verdict, and collect the output PNGs.
• 🔍 Introspect your live install — search the nodes, models, and templates your ComfyUI actually has (custom nodes included), not a static catalog.
• 🧩 Build workflows — validate a graph, edit a template's slots, and fan one workflow into variants.
• ♻️ Manage ComfyUI — launch / stop / restart the server, tail its logs, and stage input assets.

Each tool shells out to the comfy command with --where local --json, parses comfy-cli's envelope/1 output, and returns it — comfy-cli is the engine, and by default everything targets the ComfyUI on your machine (127.0.0.1:8188).

Scope — local-first, not local-only. A few flows already reach beyond your machine: partner_generate runs hosted partner models (Flux / Ideogram / Kling / …) entirely on partner infrastructure — no local ComfyUI in the execution path — and partner-API nodes let a locally-executed workflow call those same hosted models, while COMFYUI_URL points the run/job tools at a ComfyUI on another machine you control.

This server vs. Comfy Cloud MCP. Two different servers, and running both is normal. This one is stdio: your client launches it as a subprocess on your own machine, and it drives the ComfyUI installed there (or one on another machine you control). Comfy Cloud MCP is a remote HTTP server at https://cloud.comfy.org/mcp that your client connects to over the network, and it executes workflows on Comfy Cloud GPUs — no local GPU, no ComfyUI install. Both authenticate: this one signs in to Comfy through comfy-cli (auth_login or COMFY_API_KEY), the cloud one through OAuth in your browser or a Comfy Cloud API key. Both can spend credits on partner models, so partner generation is not the dividing line — what this server has no path to is Comfy Cloud itself: no cloud-hosted execution, no cloud queue, no cross-session cloud batches. Every tool here shells out to comfy --where local. Pick by where you want the work to run, or install the cloud server too.

Status: beta. 39 tools; core loop validated end-to-end against a live local ComfyUI (server_info → run_workflow → fetch_outputs → PNG on disk). CI runs pytest + ruff on Python 3.10 and 3.14.

Quickstart

Four steps take you from a fresh install to your first generated image.

1. Install the pieces.

   pip install "comfy-cli>=1.14.0"  # the engine (>= 1.14.0 required)
   comfy install                  # create a ComfyUI workspace (skip if you have one)
   pip install .                  # this MCP server → the `comfy-mcp` command
   

   Run that last one from a checkout of this repo (pip install -e . for a working copy). pip install . puts a comfy-mcp console script on your PATH; that command is what you point your AI client at in step 3. (A dedicated venv is fine — MCP clients may not see that venv's PATH, which is exactly what COMFY_BIN is for; see Prerequisites.)

   Installed this server back when it was called comfy-local-mcp? Do Upgrading from comfy-local-mcp first — pip install . alone will not clean up after the old name.

2. Launch ComfyUI and leave it running:

   comfy launch
   

3. Add the server to your client using the snippet for your client in Configure your AI client just below, then restart / reload it so the tools appear.

4. Ask your agent to run a workflow. For example:

   "Confirm my local ComfyUI is running, then run the workflow at ~/workflows/txt2img.json and show me the image."

   Under the hood the agent calls server_info to confirm ComfyUI is up, run_workflow to execute your workflow JSON (API-format or a UI export), and fetch_outputs to collect the result. No hand-authored workflow? Ask it to start from a template instead — it can search_templates, fetch_template to write a runnable JSON, and run that — and fetch_template tells it up front if your install can't run that template yet.

Where the images land. ComfyUI writes generated files into your ComfyUI workspace's output/ directory (part of the workspace comfy install created). On top of that, fetch_outputs(prompt_id, out_dir) copies a finished job's outputs into any directory you name — so telling the agent "save them to ./outputs" puts a copy right where you asked while the originals stay in the ComfyUI workspace.

Upgrading from comfy-local-mcp

This server used to be called comfy-local-mcp. It was never published to PyPI under that name, so this only affects you if you installed it from a source checkout — but for those installs the rename is not something pip install . finishes on its own, because comfy-mcp is a different distribution, not a new version of the old one. Four things moved:

Was	Is now
distribution / import package comfy-local-mcp / comfy_local_mcp	comfy-mcp / comfy_mcp
console script comfy-local-mcp (the "command" in your client config)	comfy-mcp
env var COMFY_LOCAL_MCP_DEBUG_LOG	COMFY_MCP_DEBUG_LOG
failure-log directory leaf comfy-local-mcp/	comfy-mcp/

1. Uninstall the old distribution first. Installing the new one leaves the old one in place, and its comfy-local-mcp script stays on your PATH pointing at a package that no longer exists — so an "upgraded" environment either keeps running the old code or fails with ModuleNotFoundError:

   pip uninstall comfy-local-mcp   # then: pip install .   (or `pip install -e .`)
   

2. Change "command" to comfy-mcp in every MCP client config that starts this server (.mcp.json, claude_desktop_config.json, ~/.cursor/mcp.json — see Configure your AI client), then restart the client. The old command name is gone; nothing aliases it.

3. Rename the failure-log env var if you set it. COMFY_LOCAL_MCP_DEBUG_LOG is no longer read, and an env block that still sets it logs nothing — a disabled log and a stale variable look identical from the outside. Use COMFY_MCP_DEBUG_LOG; see Failure log (opt-in).

4. Move an existing failure log if you're mid-investigation. The default path's directory leaf changed with the package, so a fresh run starts an empty failures.jsonl rather than appending to the trail you were collecting. Nothing reads the old directory any more — copy it across, or delete it:

   # macOS; ~/AppData/Local on Windows, ~/.config on Linux
   cd ~/Library/Application\ Support
   mkdir -p comfy-mcp
   mv comfy-local-mcp/failures.jsonl* comfy-mcp/ && rmdir comfy-local-mcp
   

   The glob carries the two rotations (failures.jsonl.1, failures.jsonl.2) along with the live file, and mkdir -p first means this is also safe once the new directory exists.

Configure your AI client

All three clients speak the same MCP stdio contract: run the comfy-mcp command as a server. Pick your client.

The server key (comfy-mcp in every snippet below) is just the label your client files these tools under — it is yours to choose, and the "command" (comfy-mcp) is the only part that has to match the installed console script. Earlier versions of this README used comfy-local, so if your config already has a comfy-local entry, edit it rather than pasting a second one — two keys pointing at the same command register the server twice and your client shows every tool twice. Keeping the old key is equally fine; nothing reads it.

The COMFY_BIN env entry is shown in every example. Drop it if comfy is already on the environment your client launches the server with; keep it (pointing at the absolute path) if it isn't. COMFY_API_KEY is also shown, commented as optional — keep it only if you use partner-API nodes (Seedream / Veo / Kling / Gemini / …); drop it otherwise.

On macOS, keep ComfyUI out of ~/Documents, ~/Desktop and ~/Downloads — or grant your client Full Disk Access. macOS blocks apps (and everything they launch) from reading those folders, so an install there fails with Operation not permitted before anything runs. See Troubleshooting.

Claude Code

One command registers the server:

# COMFY_API_KEY is optional — add it only if you use partner-API nodes
# (see the Partner-API nodes section).
claude mcp add comfy-mcp \
  -e COMFY_BIN=/path/to/venv/bin/comfy \
  -e COMFY_API_KEY=<your-comfy-api-key> \
  -- comfy-mcp

Or, to check it into a project, add a .mcp.json at the repo root:

{
  "mcpServers": {
    "comfy-mcp": {
      "command": "comfy-mcp",
      "env": {
        "COMFY_BIN": "/path/to/venv/bin/comfy",
        "COMFY_API_KEY": "<your-comfy-api-key>"
      }
    }
  }
}

Claude Desktop

Edit claude_desktop_config.json (Settings → Developer → Edit Config; on macOS it lives at ~/Library/Application Support/Claude/claude_desktop_config.json) and add the server, then restart Claude Desktop:

{
  "mcpServers": {
    "comfy-mcp": {
      "command": "comfy-mcp",
      "env": {
        "COMFY_BIN": "/path/to/venv/bin/comfy",
        "COMFY_API_KEY": "<your-comfy-api-key>"
      }
    }
  }
}

Cursor

Add the server to ~/.cursor/mcp.json (global) or .cursor/mcp.json in a project:

{
  "mcpServers": {
    "comfy-mcp": {
      "command": "comfy-mcp",
      "env": {
        "COMFY_BIN": "/path/to/venv/bin/comfy",
        "COMFY_API_KEY": "<your-comfy-api-key>"
      }
    }
  }
}

Comfy Cloud MCP

Everything above sets up this server, which runs on your machine. Comfy also runs a hosted MCP server — Comfy Cloud MCP — and it is a good fit when the machine can't carry local diffusion, or when you'd rather not install ComfyUI at all. It lives at:

https://cloud.comfy.org/mcp

Your client connects to that URL over remote HTTP (no subprocess, nothing to pip install) and workflows execute on Comfy Cloud GPUs. You need a Comfy Cloud account — sign up first if you don't have one, since the sign-in below uses it.

Two ways to authenticate. OAuth is the default: your client opens a browser, you pick a workspace, and tokens refresh themselves. For clients that don't speak MCP OAuth (Cursor today) and for headless/CI use, create a Comfy Cloud API key at platform.comfy.org/profile/api-keys — it starts with comfyui- — and pass it as an X-API-Key header. Prefer your client's env interpolation (${env:COMFY_API_KEY}) over pasting a key into a file you might commit.

Note that this is a separate credential path from the COMFY_API_KEY this server's own examples show: that one is read by comfy-cli on this machine for partner-API nodes. The same key works for both, but each server is configured on its own.

Claude Code (cloud)

Install the comfy-cloud plugin — it registers the MCP connection and adds /comfy-cloud:* slash commands in one step:

/plugin marketplace add Comfy-Org/comfy-skills
/plugin install comfy-cloud@comfy-skills

Then run /mcp, select comfy-cloud → Authenticate, and finish the sign-in in your browser.

Prefer just the connection, without the plugin? Add the server directly (-s user makes it available in every project):

claude mcp add --transport http comfy-cloud https://cloud.comfy.org/mcp

and authenticate the same way, via /mcp.

Claude Desktop (cloud)

Claude Desktop adds it as a custom connector through its UI:

1. Sidebar → Customize → Connectors.
2. Click + in the Connectors header → Add custom connector.
3. Name it (e.g. Comfy Cloud MCP), set Remote MCP server URL to https://cloud.comfy.org/mcp, and click Add.
4. A browser window opens: choose your workspace and click Continue to authorize.

Cursor (cloud)

Cursor connects to remote MCP servers over HTTP but does not support MCP OAuth today, so use an API key. Add this to ~/.cursor/mcp.json (global) or .cursor/mcp.json (project), with COMFY_API_KEY set in your shell or system environment:

{
  "mcpServers": {
    "comfy-cloud": {
      "url": "https://cloud.comfy.org/mcp",
      "headers": {
        "X-API-Key": "${env:COMFY_API_KEY}"
      }
    }
  }
}

Other clients (cloud)

Any client with a remote HTTP MCP transport can connect to the same URL. Most use a JSON config with a url field (Windsurf uses serverUrl instead):

{
  "mcpServers": {
    "comfy-cloud": {
      "url": "https://cloud.comfy.org/mcp"
    }
  }
}

Sign in through the browser if the client supports MCP OAuth; otherwise add the X-API-Key header shown above. Restart the client and you should see the cloud tools (search_templates, submit_workflow, get_output, …) registered under the comfy-cloud server.

Codex and OpenClaw have first-class setup steps — including codex mcp add comfy-cloud --url https://cloud.comfy.org/mcp and openclaw mcp set / openclaw mcp login — in the Comfy Cloud MCP docs, which is also where the screenshot walkthroughs, the full cloud tool list, and the slash-command/prompt tables live.

Table of contents

• Quickstart
• Upgrading from comfy-local-mcp
• Configure your AI client
• Comfy Cloud MCP
• Prerequisites
• When to use this server
• Using with local LLMs (VRAM coordination)
• Partner-API nodes
• Spending credits on partner models
• Templates your install can't run
• Driving a remote ComfyUI
• Targeting a non-default ComfyUI address
• Which address variable do I want?
• Project anchoring
• Tools
• Troubleshooting
• Failure log (opt-in)
• Smoke test
• Contributing
• License
• Trademarks

Prerequisites

• Python ≥ 3.10.
• comfy-cli ≥ 1.14.0 on your PATH: pip install "comfy-cli>=1.14.0". This is the engine every tool wraps; the server refuses to run against an older comfy-cli with an upgrade message. 1.14.0 is the first release carrying everything this server needs. 1.13.0 brought the basics — the comfy logs verb, the envelope/1 contract, the comfy outdated verb behind server_info's freshness block, and the machine-readable login_url event auth_login waits for — but a large slice of the tool surface calls verbs that only exist from 1.14.0 on: comfy node deps (node_dependencies), system-stats / free, workflow notes (list_workflow_notes), logs --port, the background download group (--background plus download-status / downloads / download-cancel), models search's cross-folder walk, the templates gallery cache TTL, and comfy run's --allow-spend interlock. On 1.13.0 enough of the surface is inert that the server reads as broken rather than as out-of-date, which is why the floor moved rather than each tool degrading.
• Every capability degrade is still in place, because the floor and a degrade guard different failures: the floor catches a wrong comfy-cli version, a degrade catches a correct version in a broken environment. The version guard fails open on a --version it can't parse (a source build, a fork), so such a build can still reach the tools from below the floor — and a dependency outside comfy-cli (a ComfyUI-Manager too old to know a flag comfy-cli forwarded to it) can fail on an otherwise-compliant install. In those cases you get a named capability gap — {"error": "…", "unsupported": true}, e.g. freshness: {"error": "freshness unavailable: …", "unsupported": true} — rather than a raw Click usage dump, and the rest of the tool keeps working.
• A ComfyUI workspace. If you don't have one, comfy-cli can create it: comfy install sets up a ComfyUI workspace it will point at. (An existing ComfyUI checkout works too — see comfy set-default <path>.)
• A running ComfyUI. ComfyUI must be started before you use the tools — launch it with comfy launch (or, from an agent, the launch_comfyui tool), and confirm it is up with server_info. Nothing here starts ComfyUI implicitly.

Optional environment variables (COMFY_BIN, COMFY_API_KEY, COMFYUI_URL, COMFY_MCP_REMOTE_SHARED_MODELS, COMFY_LOCAL_URL, COMFY_T2I_TEMPLATE; plus COMFY_USER_AGENT, which the server sets itself)

• COMFY_BIN override (optional). By default the server calls comfy from PATH. MCP clients launch the server with their own environment, which often does not include your shell's PATH — so if comfy lives in a virtualenv or a non-standard location, set COMFY_BIN to its absolute path (e.g. /path/to/venv/bin/comfy). Every example in Configure your AI client shows where it goes. Setting it is sufficient on its own — you do not also have to put that directory on the client's PATH. The server prepends the resolved binary's directory to the PATH it hands comfy-cli, because some comfy-cli commands (notably the background launch) re-invoke comfy by name and have to be able to find themselves.
• COMFY_API_KEY (optional — needed only for partner-API nodes). Workflows that use partner-API nodes (Seedream / Seedance / Nano Banana / Gemini / Veo / Kling / …) need a Comfy credential, and — exactly like COMFY_BIN — an MCP client launches the server with its own minimal environment, so a key from your shell won't reach it. Set COMFY_API_KEY in the client registration env block. See Partner-API nodes below for the full precedence chain; every example in Configure your AI client shows where it goes.
• COMFYUI_URL / COMFYUI_HOST / COMFYUI_PORT (optional — drive a ComfyUI on another machine). Read by this server. By default every tool targets 127.0.0.1:8188. Set COMFYUI_URL (e.g. http://gpu-box:8188) — or the COMFYUI_HOST (+ optional COMFYUI_PORT, default 8188) pair — to point the submit / job tools at a ComfyUI running elsewhere, e.g. a GPU box reachable over a private network (Tailscale). See Driving a remote ComfyUI for what is and isn't remoted. Unset ⇒ nothing changes.
• COMFY_MCP_REMOTE_SHARED_MODELS (optional — only meaningful alongside the variables above). download_model writes to this machine's models dir and has no remote mode, so with a remote configured it refuses rather than downloading onto the wrong disk. Set this to 1 when this machine's workspace models dir is the remote's — shared storage, e.g. an NFS / tailnet mount — to skip that guard and download as usual. Nothing else reads it, and it does nothing at all when no remote is configured.
• COMFY_LOCAL_URL (optional — a ComfyUI on this machine, on a non-default port). Read by comfy-cli, never by this server — it rides the environment passthrough, so setting it in the client env block re-points every tool. For a ComfyUI on this machine that isn't on 127.0.0.1:8188 (e.g. :8189 because Docker Desktop's ComfyUI holds :8188). See Targeting a non-default ComfyUI address, and Which address variable do I want? for the difference between the two.
• COMFY_USER_AGENT (set by the server — not yours to configure). Every comfy-cli call this server makes is labelled comfy-mcp, which is how comfy-cli tells work that came from this MCP apart from a human typing the same command — most usefully on the partner-API calls that spend credits. A value you set is overridden, on purpose: it would otherwise file this server's calls under someone else's name. The label is a caller identity, not content — nothing about your prompts, workflows, or outputs travels with it, and comfy-cli's own telemetry stays subject to comfy-cli's consent settings (comfy tracking disable, or the DO_NOT_TRACK / COMFY_NO_TELEMETRY environment variables, both of which this server passes straight through).
• COMFY_T2I_TEMPLATE / COMFY_T2I_PROMPT_SLOT / COMFY_T2I_CHECKPOINT_SLOT (optional — retarget generate_image). generate_image(prompt) runs the gallery's default template (ComfyUI's own basic SD1.5 text-to-image graph), filling its positive-prompt slot 6.text and, when you pass checkpoint, its ckpt_name slot. To point that on-ramp at a different local text-to-image graph, set all three together — the slot keys describe one specific template, so changing the template alone leaves the prompt address matching no slot. List a replacement's slots with comfy templates fetch <name> -o wf.json && comfy workflow slots wf.json. For a one-off run of some other template, prefer the run_template tool over these.

When to use this server

Local diffusion is only a good default on a machine that can actually carry it, so the server's client instructions tell your agent to read server_info's hardware block (os, arch, ram_bytes, and a gpu object with vendor / model / vram_bytes / unified_memory) before the first generation and route on it. The agent does not even have to make that call: at startup the server probes comfy env once and appends a Machine snapshot section — the same hardware block verbatim, plus the configured remote target if any — to the instructions the MCP handshake carries, so the routing figures are in the agent's context from the first message. The probe is best-effort: if it fails (no comfy on PATH yet, a timeout), the section is simply absent and the instructions still say to call server_info first; a healthy probe on an older comfy-cli that reports no hardware states the figure is unknown, which routes to step 3 below (ask). The snapshot never carries live state — whether a server is running stays server_info's job. The thresholds:

Machine	Guidance
Discrete GPU, ≥ 24 GB VRAM	Local generation is a good default.
Discrete GPU, 8 GB to under 24 GB VRAM	Images are fine (prefer current, smaller models); video will be slow or infeasible.
< 8 GB VRAM, or the user confirming there is no GPU	Don't run local diffusion. Use partner nodes (plain web calls, fine on any machine) or the Comfy Cloud MCP if your client has it connected.
Apple Silicon, ≥ 32 GB unified memory	Images are OK. Video on the Apple GPU is not recommended — time estimates are unreliable and thermals suffer.
Apple Silicon, under 32 GB unified memory	Same as the no-GPU row above — go partner/cloud rather than local.

The discrete-GPU rows are written for NVIDIA but apply to an AMD or Intel card on a ROCm/XPU build too — the VRAM number is what matters. The no-local-video rule is an Apple GPU rule rather than a Mac rule: an Intel Mac with a discrete card follows the discrete-GPU rows.

The instructions walk these as an ordered procedure, because several of the checks only make sense in sequence:

1. Is the work even local? hardware describes the machine this server runs on, and that is where most tools execute. A comfy_target block (Driving a remote ComfyUI) diverts every tool that submits a job — run_workflow, generate_image, run_template — along with the queue/jobs tools, while discovery, templates, downloads, outputs and the lifecycle tools stay here; so against a genuine remote the thresholds below describe the wrong machine. It counts as another machine only when its host is neither loopback (anything in 127.0.0.0/8, localhost, IPv6 ::1) nor this host's own address, and a malformed config produces an error-shaped {error, note} block that resolves no remote at all. Nothing the server returns carries the local hostname or interface addresses, so a host the agent can't place is a question for you rather than a guess — a hostname or LAN IP can be this same machine, and a loopback host can be a tunnel to a remote GPU. COMFY_LOCAL_URL is a second signal worth checking: it repoints comfy-cli without producing a comfy_target block.
2. Get a memory figure. The sizes are bytes (ram_bytes, gpu.vram_bytes) and the divisor gives GiB, while drivers report under the advertised size — a consumer 24 GB card reads 23.99, an ECC/reserving datacenter card (A10, L4) about 22.3 — so a small shortfall, within ~10% of a nominal size, reads as that nominal capacity. A gap wider than that is not driver overhead and is taken at face value instead: on a MIG/vGPU partition the model string names the whole card while vram_bytes is the slice you actually get, and rounding a 6 GB A100 slice up into the ≥ 24 GB band would OOM the run. On Apple Silicon gpu.vram_bytes is null (with gpu.unified_memory true) and the figure is ram_bytes — an Apple-only substitution.
3. If the figure is missing, ask. A null or zero vram_bytes on any non-Apple GPU (a discrete card comfy-cli can't size, but also a non-Apple unified part like a Jetson/Grace board or a Strix Halo APU), a missing gpu object, or a missing/zero ram_bytes on the Apple path all mean unknown, not "no GPU" — the agent asks rather than stranding a machine that has one. The "no GPU" verdict is reserved for a confirmed absence, and the only thing that confirms one is your own answer: no hardware payload encodes it, because a null or missing gpu is unknown by this same step. Nothing in this repo probes hardware, and the instructions tell the agent not to shell out either: a probe runs on a path this server can neither bound nor audit.
4. Route on the figure, then redirect rather than dead-end when the answer is "not on this machine". A figure that came from your answer rather than the payload routes on whichever row fits the machine — the unified-memory row on an Apple Silicon Mac, the VRAM rows otherwise, which is what covers the non-Apple unified-memory boards that have no row of their own.

"No local video on a Mac" is about the Apple GPU, not about video as such: API-tagged video templates (search_templates(tag="API", type="video") — both filters, since neither alone isolates partner-run video; the rows' tags then confirm what came back) and emit_partner_workflow run the model on partner infrastructure, so they work on any machine. See Partner-API nodes.

The hardware block comes straight through from comfy env, and a comfy-cli that predates it simply omits the key. There is no HTTP client and no cloud code here — the cloud/partner steer is guidance text only.

Which model to use is deliberately not encoded here. The instructions tell the agent to pick via search_templates / search_models rather than assume a classic default (e.g. SDXL), because the gallery tracks current models and a hardcoded name would rot. Current-model guidance lives in Comfy-Org/comfy-skills, which is its canonical home.

Using with local LLMs (VRAM coordination)

Running a local LLM (Ollama, LM Studio, llama.cpp) and ComfyUI on the same GPU means the two compete for the same VRAM, and the LLM is usually the one holding it when the image job needs it. This server gives the agent both halves of the read/free loop, but the coordination is the client's — see why below.

The recipe, in order:

1. Read the headroom. system_stats() returns per-device vram_free / vram_total straight from the live ComfyUI. Compare vram_free against what the workflow's checkpoint needs.
2. If it is tight, the client unloads its own LLM using its runtime's own mechanism — this server has no way to do it (step 5 below):
   • Ollama — send keep_alive: 0 on the next /api/generate (or /api/chat) call, which unloads the model as soon as that call returns, or run ollama stop <model>.
   • LM Studio — let the model's TTL / JIT auto-evict expire, or unload explicitly with lms unload <model> (lms unload --all for everything).
   • llama.cpp (llama-server) — in router mode (started with no -m, or with --models-dir) POST /models/unload with {"model": "<name>"} unloads one model; GET /models lists what is currently loaded. Independently of router mode, --sleep-idle-seconds N makes the server unload the model and its KV cache after N idle seconds and reload it automatically on the next request — which handles both step 2 and step 5 with no orchestration at all. Only a classic single-model server started without either (llama-server -m model.gguf) has nothing to call: there, stopping and restarting the process is the reclaim.
3. Free ComfyUI's own models too with free_memory(). ComfyUI applies it when its queue worker next iterates — immediate if idle, after the current job if busy — and it never interrupts a running job. Re-read system_stats() to confirm the VRAM actually came back before committing to a big run.
4. Run the job — run_workflow(...) / run_template(...) / generate_image(...) — then collect with fetch_outputs(...). (This whole recipe is about this machine's VRAM: system_stats and free_memory are never remoted, so with a COMFYUI_URL configured steps 1–3 measure and free the wrong box while step 4 submits to the remote. See Driving a remote ComfyUI.)
5. The client reloads its LLM afterwards, again through its own runtime. Ollama, LM Studio and a sleep-idle llama-server all reload on demand, so for those "reload" is just the next request; a single-model llama-server stopped in step 2 has to be started again.

Why steps 2 and 5 cannot live in this MCP server. This server is a stdio subprocess of your MCP client — it holds no handle on whatever LLM runtime that client is using, is not told which one it is, and has no business reaching into a process it does not own. Reaching one anyway would also breach the thin-wrapper rule: every tool here is a comfy passthrough, and there is no comfy subcommand for "unload someone else's model". The deeper reason is step 5: the model that was unloaded cannot ask for itself back, so something still running has to sequence unload → run → reload. Where the LLM's own runtime can do that (Ollama's on-demand load, LM Studio's JIT, llama-server --sleep-idle-seconds) it should — that is the least-coordination option and it needs nothing from this server. Otherwise the client, or the orchestrator driving it, is the only participant present throughout. Either way the split is structural rather than a missing feature: this server owns reading and freeing ComfyUI's memory, and the client owns its own model's lifecycle.

A note on scope: free_memory() asks ComfyUI to release its models. It does nothing about VRAM held by an LLM runtime, a browser, or another process — if system_stats() still shows little free VRAM after a free_memory() call, the memory is probably someone else's and step 2 is what reclaims it.

Read that signal against the lag, not instantly. The free applies on the queue worker's next iteration, so on a busy server an immediate re-read legitimately shows no change while the VRAM is still ComfyUI's — the request simply has not been serviced yet. Before concluding the memory belongs to another process, either wait for the current job to finish (job(action="queue") shows whether one is running) or re-poll system_stats() a few times over a few seconds. Only a number that stays flat on an idle server means the holder is someone else.

A second caveat: system_stats() and free_memory() are not redirected by COMFYUI_URL / COMFYUI_HOST — they always describe and act on whichever ComfyUI comfy-cli itself targets, because comfy system-stats and comfy free take no --host / --port. With a remote ComfyUI configured, run_workflow / generate_image / run_template submit there while these two read and free the local install, so this recipe applies to a local-ComfyUI setup. Don't gate a remote run on it. Both payloads say so themselves when a remote is configured: a top-level comfy_target_note (host / port / source / note) names the target the run tools submit to and states that these numbers describe whichever ComfyUI comfy-cli itself targets, which need not be the same box — the note reports that divergence rather than adjudicating it, since a configured host can perfectly well resolve to this machine (and a loopback one can be a tunnel to a remote GPU). A malformed COMFYUI_URL / COMFYUI_HOST gives an error-shaped note (error / note) instead of breaking these local-only calls, so an absent key means exactly one thing: nothing is configured, and the payloads are unchanged.

Partner-API nodes

Some ComfyUI nodes call out to Comfy's partner APIs (Seedream / Seedance / Nano Banana / Gemini / Veo / Kling / …). Running one locally still needs a Comfy credential, and comfy-cli resolves it in this order (first match wins):

1. a per-call flag (not exposed by this server);
2. a live Comfy Cloud OAuth session (comfy cloud login);
3. the COMFY_API_KEY environment variable;
4. a stored key set with comfy auth set comfy-cloud-api-key --key <KEY>.

Option 2 does not have to be typed into a terminal: the agent can call auth_login, which starts comfy cloud login in the background and hands back the OAuth URL for you to open. Complete the sign-in in your browser, then have the agent confirm it with auth_status. The sign-in itself is comfy-cli's — this server never sees your tokens, and the browser callback is handled by the CLI's own loopback listener on this machine (so auth_login is for a local MCP; on a remote/containerised one, sign in where comfy-cli actually runs).

Because an MCP client spawns the server with its own minimal environment (the same reason COMFY_BIN exists), a COMFY_API_KEY from your interactive shell is not inherited — put it in the client registration env block (shown in every client example). If a run fails with partner_node_requires_credential, the error now carries comfy-cli's hint verbatim, including the comfy auth set comfy-cloud-api-key --key … fallback and the list of offending nodes; the server also retries a transient credential failure briefly before surfacing it.

Confirmation prompts on clients that can't show them

Several tools ask you to confirm before they act: install_node, update_comfyui(target="all"), switch_comfyui_version, restart_comfyui when it must stop a server it did not start, and launch_comfyui with --listen (which exposes an unauthenticated ComfyUI to your network). Each raises an MCP elicitation and fails closed if it is not approved.

Some MCP clients answer that request without ever showing you a prompt. When that happens the tool refuses and tells you so — nothing is changed, and the error names the equivalent terminal command you can run instead.

If you would rather pre-authorize specific gates, set COMFY_MCP_ASSUME_CONSENT in the server's environment — the env block of your client registration, alongside COMFY_BIN:

"env": { "COMFY_MCP_ASSUME_CONSENT": "install_node,update_all" }

Accepted names: install_node, update_all, version_switch, kill_untracked, network_exposure — or all for every one of them. List only what you want; authorizing node installs should not silently also authorize binding ComfyUI to every network interface.

This is a setting you write, in a file the model cannot edit. That is the point: an agent cannot grant itself permission by passing an argument, which is why no tool parameter does this.

Spending credits is deliberately excluded. No value — including all — pre-authorizes partner_generate, run_template or run_workflow. Money keeps a single owner: comfy-cli's own durable consent (comfy generate consent always). See Spending credits on partner models.

Spending credits on partner models

partner_generate is the one tool whose whole purpose is to spend: it wraps comfy generate <model>, which calls a hosted partner API and spends your Comfy credits. So every call is confirmed with you first.

The other tools execute on your machine, and on their own they cost nothing — but that is a property of the tool, not a guarantee about the workflow you hand it. A workflow run through run_workflow can itself contain the partner-API nodes described just above (Seedream, Veo, Kling, …), or any other node that bills a hosted service, and those still spend your credits — they bill through the workflow, below this server. run_workflow therefore carries the same opt-in confirm_spend gate run_template does (below). That gate covers the partner-API nodes comfy-cli recognizes, which is not the same as every node that can bill something: an arbitrary custom node can still call a paid service of its own, with nothing to gate it. Check what a workflow contains before running one you did not build. generate_image needs no gate because it runs a free OSS template — though note it is retargetable via COMFY_T2I_TEMPLATE, and pointed at an API-tagged template it would spend with no prompt.

emit_partner_workflow sits on the free side of that line for the same reason: it only writes a graph containing a partner API node, never calls the partner, and so has no confirmation prompt. The graph it writes is exactly one of the workflows the paragraph above is warning about — running it with run_workflow bills the partner node, so that step needs confirm_spend=True.

On a client that supports MCP elicitation (Claude Code and Claude Desktop do), the call raises a confirmation prompt naming the model and saying that it spends credits:

• Approve → the server forwards comfy-cli's --yes and the generation runs.
• Decline (or dismiss it) → the tool returns an error, and comfy-cli is never started. No credits are spent.
• Leave it unanswered → after five minutes the prompt lapses into a refusal, so a forgotten call never sits pending forever. Nothing is spent; call the tool again to get a fresh prompt.

Don't want to be asked every time? Persist it in comfy-cli, not here:

comfy generate consent always   # spend without prompting
comfy generate consent show     # what is it set to?
comfy generate consent ask      # back to confirming each call

The server reads that setting per call and skips its own prompt when it is on — the durable "always proceed" lives in comfy-cli's config, and this server keeps no spend state of its own.

On a client that cannot elicit, there is no prompt to raise, so consent has to be explicit in the call: confirm_spend=True forwards --yes. Without it comfy-cli's gate fails closed (an MCP server has no terminal to prompt at) and the call errors having spent nothing. On a client that can elicit you are asked anyway — confirm_spend=True is not a way around the prompt.

Two things the server deliberately will not do:

• Treat tool permission as spend consent. Your agent host's "always allow this tool" toggle authorizes calling partner_generate; it never authorizes spending your money, and is never read as consent. Only the prompt you answered, or the comfy-cli setting you persisted, is.
• Run against a comfy-cli with no spend gate. The fail-closed guarantee is the engine's, so if comfy generate consent is missing the tool refuses up front rather than spending on the assumption something would have stopped it. pip install -U comfy-cli to fix.

Templates that spend — run_template

run_template is the other tool that can spend, and it is confirmed the same way, with the differences the verb forces. Most gallery templates are free OSS graphs that run on your machine; some embed partner-API nodes and bill through them.

• confirm_spend=False (the default) never prompts. Nothing is forwarded, so comfy-cli's gate fails closed on a paid template — there is nothing to consent to. A free template just runs. This is deliberate: prompting on every template run would train you to click through the one prompt that matters.
• confirm_spend=True asks you first, naming the template, on any client that can elicit. Approve → --allow-spend is forwarded. Decline → the tool errors and comfy-cli is never started. As with partner_generate, an agent setting the argument for itself is not your consent; on a client that cannot elicit it stands alone as the fallback.
• comfy generate consent always does not apply here. That setting is scoped to comfy generate — comfy run-template never reads it — so it grants nothing for templates and the prompt is raised regardless.

Unlike partner_generate, there is no up-front gate probe: run-template carries its spend gate inside the verb itself, so a comfy-cli that has the verb has the gate.

Workflows that spend — run_workflow

run_workflow takes the same confirm_spend argument, with the same three rules as run_template above — default never prompts and forwards nothing, confirm_spend=True asks you per call on a client that can elicit, and comfy generate consent always grants nothing here either. Most workflows are ordinary local graphs and are unaffected; the ones this matters for are the graph emit_partner_workflow writes and an API-tagged gallery template you fetched with fetch_template. When consent is withheld the engine refuses with spend_consent_required and names the offending partner_nodes, so you learn which nodes cost money without a second call. Consent is resolved once per call, so the server's brief credential retry never re-asks you.

One caveat specific to this verb, and the reason it is called out rather than folded into the section above: comfy run long predates its spend gate, so unlike run-template the verb's presence proves nothing. The gate shipped in comfy-cli 1.14.0, which is the floor this server enforces, so on every published comfy-cli it accepts the interlock is there and confirm_spend=False is a guarantee rather than a default. The probe stays because the floor can't prove it: the version guard fails open, so a source build or fork whose --version can't be read reaches the tool without the flag. The server probes comfy run --help on the calls you approved and simply omits --allow-spend when that comfy-cli has no such flag, so an approved run still runs instead of dying on a usage error — but on such a build what authorizes the spend is your answer to the prompt, not an engine gate, and a paid workflow runs and spends whether or not you pass confirm_spend. pip install -U comfy-cli closes that residual case.

Templates your install can't run

The template gallery is served fresh from Comfy-Org/workflow_templates, while your ComfyUI is whatever version you installed. So the catalog can legitimately offer a template your install cannot run yet — it references a node class you don't have, or a model option inside a node you do have (a partner model key added in a later release is the common one). Discovery succeeds, the run fails, and you get to work out why.

get_template and fetch_template cross-check the template against your install and report it as a local_check block. Under the hood it is comfy validate — the same engine validate_workflow uses, reading the live object_info of your running ComfyUI, so it sees your custom nodes and your model options, not a bundled catalog.

local_check	Means
{"checked": true, "runnable": true, …}	Every node class and input option the template uses exists in your install. Necessary, not sufficient — validate_workflow's documented blind spots still apply.
{"checked": true, "runnable": false, "errors": [...], …}	Running it will fail as-is: the errors name what is missing (and, where comfy-cli can, what your install offers instead). Update ComfyUI and its custom nodes, or pick another template.
{"checked": false, "reason": …, …}	The comparison could not be made — almost always because ComfyUI isn't running, so there is no live catalog to compare against. This is not a verdict about the template.

The check is advisory and fails open: the workflow file is written either way, path always comes back, and nothing is ever refused on its account. Pass check_local=False to skip it.

Driving a remote ComfyUI

By default the server drives ComfyUI on the local 127.0.0.1:8188. Point it at a ComfyUI running elsewhere — e.g. a GPU box reachable over a private network (Tailscale) — by setting one of:

• COMFYUI_URL — a full URL, e.g. http://gpu-box:8188 (host-only is fine; port defaults to 8188). Takes precedence over the pair below. Only the host and port are forwarded to comfy-cli, so the URL must be plain http:// with no base path and no query or fragment: an https:// scheme, a reverse-proxy path (http://gpu-box:8188/comfyui), or a query / fragment / ;params (http://gpu-box:8188/?token=…) is rejected rather than silently downgraded to http / dropped. That last one is the shape an auth-proxied ComfyUI is usually written as, and comfy-cli has nowhere to put it — a dropped token would submit every run unauthenticated and fail later as a 401/403 naming nothing — so it is refused up front. Front a TLS/base-path/auth proxy locally if you need one, and point COMFYUI_URL at that.
• COMFYUI_HOST (+ optional COMFYUI_PORT, default 8188) — e.g. COMFYUI_HOST=gpu-box. A port without a host (setting only COMFYUI_PORT) is rejected — set the host too.

Set it in the client registration env block (same place as COMFY_BIN). With nothing set, behavior is unchanged (127.0.0.1:8188 on this machine). If what you actually have is a ComfyUI on this machine on a different port, you want COMFY_LOCAL_URL instead — see Which address variable do I want?.

When configured, the server forwards --host / --port to comfy-cli for exactly the verbs that accept them — comfy run, comfy run-template, comfy jobs … and comfy upload — so every tool that submits a job, reads one back, or stages the files a job will read targets the remote: run_workflow, generate_image, run_template, job (every action), upload_file. server_info reports the configured target under a comfy_target block.

That set is deliberately closed under submit-then-poll: a prompt_id only means something to the server that issued it, so a tool that submits and a tool that polls must never resolve to different machines. upload_file is in it for the same reason one step earlier: an input file is only useful on the machine that runs the workflow reading it, so staging it here while submitting there would fail the run on a filename the remote cannot see. Its paths still name files on this machine — they are read here and their bytes sent to the target. Remote upload needs comfy-cli ≥ 1.14.0 (this server's floor); an older one rejects the forwarded --host and upload_file raises with the upgrade step rather than silently staging into the local input dir.

Not remoted (this repo is a thin wrapper and never opens its own socket):

• Lifecycle (launch_comfyui, stop_comfyui, restart_comfyui, update_comfyui, switch_comfyui_version, install_node, get_logs) — these manage a local ComfyUI process/install and stay local-only; they cannot start/stop, update, version-switch, install node packs into, or read logs from a remote box. Start and update ComfyUI, and install its node packs, on the remote host yourself. install_node in particular writes into this machine's ComfyUI workspace and venv, so with COMFYUI_URL set the pack lands where the run isn't.
• Catalog / partner verbs — search_templates / search_models / download_model / partner_generate — this server forwards no --host/--port to these verbs (they accept none at all), so they run against comfy-cli's local default. A model must be installed on the machine that actually runs the job, and download_model cannot do that for you — so rather than writing the checkpoint to the wrong disk and letting the run fail later on a missing model, it refuses while COMFYUI_URL/COMFYUI_HOST is set, naming the remote it would have missed. Install the model on the remote host itself (its own comfy-cli or MCP server). The exception is shared storage — an NFS / tailnet mount where this machine's workspace models dir is the remote's — which no environment check can distinguish, and which this server may not probe the remote to confirm: assert it with COMFY_MCP_REMOTE_SHARED_MODELS=1 and the download runs as it always did. download (every action) is never guarded — they manage downloads already submitted here.
• Output download (fetch_outputs → comfy download) takes no --host/--port either, but it still retrieves a remote job's files, because it never asks a server which job that is: the same comfy-cli run that submitted the job wrote a state file on this machine keyed by prompt_id, and for a non-loopback target that file records each output as an absolute http://<remote>:<port>/view?… URL, which comfy download then streams from the remote. It falls back to querying the local default server only when no such state file exists (an id this machine never submitted). run_workflow(wait=True) / job(action="status") return those same URLs if you would rather hand them off than copy bytes.
• Discovery / validation (nodes, validate_workflow, and the local_check block on fetch_template / get_template) — their comfy-cli verbs do accept --host/--port, but this version forwards only to the submit/poll tools, so they still describe the local install. Remoting them is a planned follow-up; until then a workflow or template can pass a local check and still fail on a remote whose node set differs, so author/validate against a local ComfyUI matching the remote's.
• The remote ComfyUI must be reachable and unauthenticated on that network (the private network is the boundary); the server does not authenticate to it. server_info does not live-probe the remote — reachability surfaces on the first run/job call.

Targeting a non-default ComfyUI address

The section above drives a ComfyUI on another machine. This one is for a ComfyUI on this machine that simply isn't on the default 127.0.0.1:8188 — most often a port clash, e.g. Docker Desktop's ComfyUI already holds :8188 so yours came up on :8189.

That address is resolved by comfy-cli, not by this server. Every tool shells out to comfy with the server's full environment, so a COMFY_LOCAL_URL set in your MCP client's env block reaches comfy-cli and re-points every local-targeting verb. Nothing to change here — set it alongside COMFY_BIN in the client registration:

{
  "mcpServers": {
    "comfy-mcp": {
      "command": "comfy-mcp",
      "env": {
        "COMFY_BIN": "/path/to/venv/bin/comfy",
        "COMFY_LOCAL_URL": "http://127.0.0.1:8189"
      }
    }
  }
}

Accepted values. http://host:port, host:port, or http://host (port defaults to 8188; the scheme is optional and, if present, must be http). IPv6 literals are bracketed: http://[::1]:8189. A malformed value is ignored with a one-line stderr warning rather than breaking the call.

Verify it took effect — call server_info first. server_info wraps comfy env, which resolves the local address by the same rules, so the server URL it reports is the resolved address. Seeing :8189 there (and the server reported running) confirms the override is live.

Requires comfy-cli ≥ 1.14.0 (this server's floor). COMFY_LOCAL_URL itself landed after the 1.12.0 release and first shipped in 1.13.0 — below the enforced floor, so every published comfy-cli this server accepts honors the variable. The floor is not a guarantee, though: the version guard fails OPEN on a --version it can't parse, that errors, or that times out, so a source build or fork older than 1.13.0 can still slip past it and silently ignore the variable. On any comfy-cli without the support the variable is simply ignored (no error) and every tool keeps targeting 127.0.0.1:8188 — which is why the server_info check above is the way to confirm it took effect, rather than the version alone.

Still reporting :8188? Three causes, all silent, in the order worth checking:

1. The value never reached comfy-cli — it's in the wrong env block, or the client wasn't restarted after the edit. The workspace/Python fields server_info reports confirm which comfy-cli install you're actually talking to.
2. The value is malformed — comfy-cli ignores it and falls back to 127.0.0.1:8188, emitting only a one-line stderr warning that this server's success path discards, so a typo (https://… — only http is accepted; a non-numeric port; a port outside 1–65535) looks exactly like the other two causes from the MCP side. Confirm by running COMFY_LOCAL_URL=<your value> comfy env in a terminal and reading stderr; see Accepted values above.
3. comfy-cli is too old — it predates the variable and ignored it. server_info's compatibility.comfy_cli_version reports the detected version.

Precedence (comfy-cli resolves this, first match wins): an explicit --host/--port flag → COMFY_LOCAL_URL → a comfy-cli-launched background server → 127.0.0.1:8188.

Which address variable do I want?

Two variables point ComfyUI work at an address, their names are similar, and they are not alternative spellings of each other — they belong to different programs and are read at different layers. Pick by which one you need; the table is the whole answer.

	COMFYUI_URL (+ COMFYUI_HOST / COMFYUI_PORT)	COMFY_LOCAL_URL
Read by	this MCP server (_comfy_target)	comfy-cli (comfy_cli/local_address.py); this server never reads it
Means	"a ComfyUI on another machine I control"	"the ComfyUI on this machine is not on 127.0.0.1:8188"
How it acts	this server forwards --host / --port to the verbs that accept them	comfy-cli resolves its own target from the environment it inherits
What it moves	the submit / job tools plus upload_file (run_workflow, generate_image, run_template, the jobs family, and input staging) — see what is and isn't remoted	every verb, including the ones that take no --host / --port (comfy env, templates, models, download)
Reported as	a comfy_target block on server_info	the resolved server URL on server_info — no comfy_target block
Use it for	a GPU box over Tailscale / a private network	a port clash, a second instance, a container publishing a different port

Set one, not both. They resolve independently, so together they split your tools rather than conflicting loudly: comfy-cli ranks an explicit --host / --port flag above COMFY_LOCAL_URL, so the submit/job tools would follow COMFYUI_URL while every other verb followed COMFY_LOCAL_URL — two different ComfyUIs, no error. For a non-default address on this machine prefer COMFY_LOCAL_URL alone, since it also reaches the verbs COMFYUI_URL cannot.

Neither name is changing, and neither is deprecated. They look like a rename waiting to happen — they are not, because only one of them is ours. COMFY_LOCAL_URL is comfy-cli's own published variable: renaming it here would document a name nothing reads, and its "local" is a factual address-scope word (comfy-cli's local target, as opposed to its cloud one), not this project's branding. COMFYUI_URL is this server's, and already carries no "local" to strip. So there is no old spelling to accept and no deprecation period to sit through — if you have either variable in an MCP client config today, it keeps working unchanged.

Project anchoring

comfy-cli 1.15.0 ships a project/1 convention (comfy project init / comfy project status, this server's project tool) — a comfy.yaml plus assets/ / fragments/ / blueprints/ / outputs/ / .comfy/ under a root directory, with status reporting recent_runs and other project-scoped state. comfy-cli resolves which project governs a call by walking up from its own process's working directory only — there is no --project flag and no env var it reads itself. That assumes a persistent shell session sitting inside the project tree; this server's own working directory is whatever the MCP client happened to launch it from, arbitrary and unrelated to any project the user has in mind — so out of the box, this server cannot participate in projects at all.

Set COMFY_PROJECT to an absolute path to fix that: every comfy-cli spawn this server makes then runs with that directory as its cwd, so comfy-cli's own cwd-walk resolves it exactly as if a shell had cd'd there first. Read from the environment once per process (a value changed mid-session is not picked up until restart) and validated on every spawn: the directory does not need to contain comfy.yaml yet — call project(action="init") for that — but it does need to exist, and it must be absolute. A relative value is rejected outright, never silently resolved against this server's own (client-assigned, arbitrary) working directory — that resolution would be exactly as non-deterministic as leaving COMFY_PROJECT unset while looking configured. A set-but-relative or set-but-missing (or non-directory) value fails closed: the next comfy-cli spawn raises rather than silently falling back to the unanchored default, because a silent fallback would reintroduce exactly the non-determinism this feature exists to remove. Fix it by setting an absolute path, unsetting COMFY_PROJECT, or creating the directory.

This also moves where relative tool arguments land. Relative path arguments (workflow_path, out_path, out_dir, …) resolve against whatever directory comfy-cli's cwd is — the project root once COMFY_PROJECT is set, not this server's original launch directory. Pass absolute paths when you mean somewhere else.

Calling project(action="init") on a root that is already governed by a project (its own or an ancestor's comfy.yaml) is not a no-op: comfy-cli raises project_already_exists rather than re-initializing it. Call project(action="status") first when unsure whether a root is already governed.

Unset (the default): behavior is unchanged. No cwd is passed to any spawn, exactly as before this feature existed — every tool keeps acting on this server's own process directory, an unanchored comfy project status returning comfy-cli's own project_not_found.

Set it in the client registration env block, same as COMFY_BIN:

{
  "mcpServers": {
    "comfy-mcp": {
      "command": "comfy-mcp",
      "env": {
        "COMFY_BIN": "/path/to/venv/bin/comfy",
        "COMFY_PROJECT": "/Users/you/comfy-projects/my-project"
      }
    }
  }
}

Tools

39 tools, grouped below by what they do. Every tool runs comfy with the global --json --where local flags, unwraps comfy-cli's envelope/1, and returns its data.

Argument naming is uniform, so an agent never has to guess it (the server's handshake instructions say the same thing): an input workflow file is always workflow_path, an output file is out_path, an output directory is out_dir, a registry lookup key is name, and a job handle is prompt_id.

Run and monitor

Tool	Wraps	What it does
run_workflow(workflow_path, wait=True, timeout_seconds=110.0, confirm_spend=False)	comfy run --workflow <path> [--wait] [--allow-spend]	Run a workflow JSON; wait=False submits async and returns a prompt_id. Most workflows are free local graphs, but one embedding partner (paid) nodes spends credits: confirm_spend=True unlocks that, and on an elicitation-capable client asks you per call, same posture as run_template. On a comfy-cli whose comfy run carries the gate the default fails closed (spend_consent_required, naming the partner_nodes); that is every release from 1.14.0 on, which the floor requires, so a paid graph only slips through on a build that got past the fail-open version guard. See Workflows that spend.
generate_image(prompt, checkpoint=None, wait=True, timeout_seconds=600.0)	comfy run-template default --param=6.text=<prompt> [--param=ckpt_name=<ckpt>]	Text prompt → image in one call, with no hand-assembled workflow needed: it runs ComfyUI's own default SD1.5 text-to-image gallery template through the same verb (and the same run path) as run_template. Free — nothing here spends credits. Runs on whichever ComfyUI the server targets, so it follows COMFYUI_URL/COMFYUI_HOST like run_workflow does (Driving a remote ComfyUI); the checkpoint has to be installed on that machine. Retarget the template with COMFY_T2I_TEMPLATE and its slot-key companions. Same envelope shape as run_workflow (prompt_id + outputs); the fast on-ramp.
partner_generate(model, params=None, confirm_spend=False, out_path=None, timeout_seconds=600.0)	comfy generate <model> [--param=value…] [--download=<path>] [--timeout=<s>] [--yes]	Run a hosted partner model (Flux / Ideogram / DALL·E / Recraft / …). Spends Comfy credits on every call, where the local run_workflow / generate_image paths spend only when the graph itself carries partner nodes. Every call confirms the spend with you first — see Spending credits below. Runs entirely on the partner's infrastructure — your local ComfyUI is never in the execution path; use emit_partner_workflow below for the path where it is. params are the model's own schema-driven inputs, forwarded verbatim — list_partner_models() gives you the model aliases and partner_model_schema(model) the parameter list, so neither needs a terminal. out_path becomes comfy-cli's --download and is a save-path template: a plain path names the file, {request_id} / {index} / {ext} are substituted per output, and a trailing slash means "a default filename in this directory". timeout_seconds becomes comfy-cli's own --timeout so the engine — not a parent kill — owns the deadline on a job the partner may already have charged for. The result carries comfy-cli's printed text as message and, when it named the files it wrote, the resolved paths as saved_paths — so a caller reads the destination as data instead of scraping prose that rich may have wrapped mid-filename.
emit_partner_workflow(model, out_path, params=None)	comfy generate <model> [--param=value…] --emit-workflow=<path>	Write a runnable workflow JSON that drives the partner model's API node instead of calling the proxy, so your own ComfyUI executes the partner model (the other way there is an existing API-tagged gallery template via search_templates / run_template; this is the path from a model alias). Chain it: emit_partner_workflow → run_workflow → fetch_outputs (the three stay separate so the graph can be inspected, edited with set_workflow_slot, re-run, or embedded in a bigger pipeline). Calls no partner API, needs no API key, and spends nothing, so unlike partner_generate it has no confirm_spend argument and raises no confirmation prompt — running the emitted graph is what bills the partner node, so that run_workflow step is the one that needs confirm_spend=True. Coverage is narrow: comfy-cli maps only flux-2, flux-pro, kling-i2v, nano-banana and seedance to a node class, a small subset of list_partner_models(); every other model reaches its partner through the proxy only, so send those to partner_generate. An unsupported model raises with comfy-cli's own emit_workflow_failed message, which names the supported set for the comfy-cli you actually have installed. Returns comfy-cli's envelope data — {"out", "model", "nodes"}.
run_template(name, params=None, confirm_spend=False, wait=True, timeout_seconds=600.0, ctx=None)	comfy run-template <name> [--param=KEY=VALUE…] [--timeout=<s>] [--allow-spend] [--async]	One-command template run — fetch the gallery template, fill its parameterized slots, and run it on whichever ComfyUI the server targets, so it follows COMFYUI_URL/COMFYUI_HOST like run_workflow does (Driving a remote ComfyUI) (the one-shot alternative to fetch_template → run_workflow). params are {slot: value} (slot address 6.text or name prompt), JSON-encoded so types round-trip. Most templates are free OSS graphs; one embedding partner (paid) nodes spends credits and fails closed unless confirm_spend=True unlocks it — and on an elicitation-capable client that asks you per call before anything runs (same posture as partner_generate; a default, free run is never prompted, and comfy generate consent always does not apply to this verb). No capability probe is needed here (unlike partner_generate): this verb's gate ships inside the verb itself, so a comfy-cli that has run-template has the gate. wait=True (the default) streams the run's live progress as MCP progress notifications, the same way run_workflow / job(action="watch") do, so a long template run is not a silent block; wait=False submits --async and returns a prompt_id. comfy-cli's --timeout for this verb is per-event, not a whole-run deadline, so timeout_seconds is forwarded only to tighten it below the engine's 120s default — prefer wait=False over a large timeout_seconds for long runs.
job(action="status", prompt_id="", timeout_seconds=None)	comfy jobs status/watch/cancel/ls <prompt_id>	One grouped tool over the six former job_status/wait_for_job/watch_job/get_execution_error/cancel_job/get_queue tools — pick a behavior with action. "status" (default) polls status + outputs. "error" returns a compact failure verdict — the failing node, exception_type/exception_message, and a bounded traceback tail — so an agent can self-repair; error: None on a healthy prompt. Failures comfy-cli diagnosed itself rather than ComfyUI (a server_died crash mid-run) carry no node-level fields, so the verdict also reports error_code — comfy-cli's own code, None on an ordinary node failure — with its message backfilling exception_message. "wait" polls (bounded, default 25.0s) until a job reaches a terminal status, returning a {"timed_out": True, …} payload on expiry — chain several rather than one long call. "watch" streams live progress (bounded, default 600.0s) as MCP progress notifications, same timed_out shape except status is a live {progress, total, nodes_done} snapshot. "cancel" stops a queued/running job. "queue" lists known jobs (Comfy Cloud-tracked rows filtered out, since this server never drives them; follows a configured remote like the other job actions). prompt_id is required for every action but "queue"; timeout_seconds only for "wait"/"watch" — passing either where the action does not use it is rejected rather than silently ignored.
fetch_outputs(prompt_id, out_dir, url_only=False, inline_images=False)	comfy download <prompt_id> --where local -o <out_dir> [--url-only]	Write a finished job's outputs into out_dir — including a job that ran on a configured remote, which comfy-cli resolves from the local prompt_id state file rather than from a server (see Driving a remote ComfyUI); url_only=True emits the output URLs without copying bytes; inline_images=True also returns the copied images as inline MCP image content so the agent can see them without a second read.

Resource management

Tool	Wraps	What it does
system_stats()	comfy system-stats	Read the live local ComfyUI's VRAM per device and system RAM. ComfyUI's whole /system_stats payload is forwarded unmodified except for a comfy_target_note key added when a remote target is configured (see below), so treat it as a passthrough, not a fixed schema: a devices list plus a system dict, whose keys are whatever that ComfyUI reports. The ones this server's guidance reads are per-device vram_free / vram_total (byte counts, alongside e.g. name, type, index, torch_vram_free) and system.ram_free / ram_total / comfyui_version — examples, not an exhaustive list. Nothing is filtered, so the system block also carries ComfyUI's python_version and argv (its full launch command line), which reach the model's context verbatim. Call it before a heavy run_workflow / run_template to decide whether to free memory first, and again afterwards to confirm the headroom landed. Read-only. Needs a running ComfyUI (the numbers come from the server), and unlike the run/job tools it is not diverted by COMFYUI_URL/COMFYUI_HOST — comfy system-stats takes no --host/--port. When one of those is set, a top-level comfy_target_note (host / port / source / note) is added naming that target and saying these numbers describe whichever ComfyUI comfy-cli itself targets — settle whether that host is this machine before gating a run on them. A malformed value gives an error-shaped note (error / note) rather than breaking the call; with nothing configured the key is absent.
free_memory(unload_models=True, free_memory=None)	comfy free [--unload-models|--no-unload-models] [--free-memory]	Ask ComfyUI to unload models from VRAM and reset its executor cache (POST /free). free_memory=None means follow unload_models, so the default call requests both — maximum headroom, and a deliberate divergence from comfy-cli's --free-memory, which defaults to off; pass free_memory=False for the CLI's lighter unload that keeps cached executor state. The cache reset can't be had without the unload: ComfyUI's worker resolves the pair as flags.get("unload_models", free_memory) and its /free handler only records unload_models when true, so unload_models=False, free_memory=True would unload everything — that pair is rejected rather than sent. unload_models=False therefore asks ComfyUI to do nothing; it's a deliberate no-op kept for symmetry with the CLI. Not immediate and never destructive: ComfyUI applies the request when its queue worker next iterates — immediate if idle, after the current job if busy — and it does not interrupt a running job, so it cannot be used to stop one (job(action="cancel") does that). Returns comfy-cli's acknowledgement of what was requested, not a measurement; read system_stats afterwards to confirm. Also not diverted by COMFYUI_URL/COMFYUI_HOST, and it carries the same comfy_target_note key when one of those is set — naming the target this call may not have freed. See Using with local LLMs.

Diagnostics

Tool	Wraps	What it does
server_info()	comfy env + comfy outdated	Is a local ComfyUI running, where, and which workspace. Call first. Passes through comfy-cli's hardware block (GPU vendor/model, VRAM or unified memory, total RAM) when the installed comfy-cli reports one — the signal behind When to use this server, which the startup Machine snapshot also carries in the handshake instructions so routing never waits on this call. Also attaches a freshness block (comfy outdated): installed-vs-latest for ComfyUI core and each custom node pack, so a stale install is flagged before it masquerades as a missing model/node. On a comfy-cli without the outdated verb the block degrades to freshness: {"error": "freshness unavailable: …", "unsupported": true} (a benign capability gap — skip staleness advice, nothing is broken); on any other probe failure such as a network error it degrades to freshness: {"error": …} carrying the real reason. Either way the tool itself still succeeds. Reports the configured remote under a comfy_target block when COMFYUI_URL/COMFYUI_HOST is set (see Driving a remote ComfyUI).
auth_status()	comfy cloud whoami	Comfy Cloud credential status for partner-API nodes (read-only, never returns secrets). Adds a local registration_env_key_present bool for the COMFY_API_KEY registration-env slot whoami can't see.
auth_login()	comfy cloud login --no-browser --timeout 600	Start Comfy Cloud sign-in and return {"status": "awaiting_browser", "login_url": …, "expires_in_s": …} — the URL for the user to open, so an agent can get them signed in instead of telling them to run the CLI by hand. Returns as soon as comfy-cli emits the URL; the sign-in keeps running in the background (comfy-cli owns the OAuth flow and the loopback callback, so no OAuth logic lives here). Confirm the result with auth_status. Only one sign-in at a time: calling it again while one is pending re-reports the same URL without spawning a second flow, and calling it after the flow ended reports completed / failed once and then clears. Never returns tokens.
which()	comfy which	Which ComfyUI install/workspace comfy-cli currently targets (a lighter answer than server_info).
project(action="status")	comfy project status / comfy project init	Report or create the operator-anchored project/1 (action="status" / "init"). See Project anchoring.
get_logs(tail=200, port=None)	comfy logs --tail <tail> [--port <port>]	Tail the background ComfyUI's captured log (<workspace>/user/comfyui_<port>.log) — closes the debugging loop after a detached launch_comfyui. Returns {lines, path, truncated}; a missing log file returns {"error": "no_log_file", …} rather than raising, and on a newer comfy-cli that message lists every candidate path checked. Pass port when several instances/ports have run, or after a crash, to force user/comfyui_<port>.log resolution. A newer comfy-cli also returns source / port_mismatch / mtime / size, forwarded untouched: if port_mismatch is true or source reports a fallback, the lines may belong to a different server — re-call with an explicit port (note user/comfyui.log, unsuffixed, is ComfyUI-Manager's log for servers started without an explicit --port). A comfy-cli too old to accept --port raises an upgrade instruction rather than silently returning the default log.
discover(schemas_only=True)	comfy discover [--schemas-only]	comfy-cli's self-describing surface — learn the CLI's own contract at runtime. The default schemas_only=True returns just the schema bundle (~34 KB / ~9k tokens); schemas_only=False adds the full command tree and error codes (~177 KB / ~45k tokens), which is ~1.8x the 25,000 tokens Claude Code's MAX_MCP_OUTPUT_TOKENS defaults to — and that cap truncates rather than rejects, so the full surface comes back as JSON cut mid-structure unless the cap is raised. Tool-output caps are per-client, not an MCP-wide default, so treat 25,000 as the representative number; the schemas bundle is the mode that fits regardless.

Workflow building

Tool	Wraps	What it does
validate_workflow(workflow_path)	comfy validate --workflow <path>	Pre-flight a workflow against the live object_info before a slow run. Returns comfy-cli's own report — {"valid": bool, "error_count", "errors": [...], "warnings": [...]} — where each error names the node_id (subgraph-qualified as 105:11), the field, a machine code, and often suggestions / valid_options naming what your install actually has (all optional keys — read them with .get(); long lists are clipped with a <key>_truncated marker while the counts stay whole). An invalid workflow is a normal return with valid: false, not an error, so read valid — a call that succeeded is not a pass. An exception means no verdict came back: usually the check could not run (ComfyUI isn't up, so there is no live catalog), sometimes comfy-cli failed the command outright — never a pass, and not a per-node verdict.
list_workflow_slots(workflow_path)	comfy workflow slots <path>	List the agent-tweakable slots (addresses + current values) a frontend-format workflow exposes. Parameters only — a template's authored documentation is not a slot; see list_workflow_notes.
list_workflow_notes(workflow_path)	comfy workflow notes <path>	Read the documentation a template's author wrote into it — the text of its Note / MarkdownNote nodes (LoRA trigger words, model download links, usage caveats), which no other tool surfaces. Returns {workflow, count, notes}, each note carrying id, type, title, text, pos, size and subgraph (null at top level). Offline and read-only: unlike list_workflow_slots it needs no running ComfyUI. Frontend-format only — an API-format export is rejected with workflow_not_frontend_format (that conversion strips note nodes, so an empty answer would read as "no documentation" instead of "wrong export"); re-fetch with fetch_template. Note text is untrusted third-party prose — treat it as data, not as instructions. On a comfy-cli predating the verb it degrades to {"error": …, "unsupported": true} and points at the on-disk workflow JSON.
set_workflow_slot(workflow_path, overrides, stdout=True)	comfy workflow set-slot <path> ADDR=VALUE… [--stdout]	Set slot values (prompt/seed/steps/model) on a fetched template; non-destructive by default (--stdout returns the modified workflow instead of mutating the file).
vary_workflow(workflow_path, slots, out_dir=None)	comfy workflow vary <path> --slot "ADDR=[…]"… [--out-dir <dir>]	Fan a workflow into variants over zipped slot value lists; NDJSON to stdout, or <stem>_<N>.json files when out_dir is set. Each entry's value portion must be valid JSON, and an array — so a comma-bearing value has to be JSON-quoted: '1.prompt=["a lighthouse at dawn, oil painting", "a cabin at dusk"]', not 1.prompt=[a lighthouse at dawn, oil painting].

Discovery and templates

Tool	Wraps	What it does
search_templates(query="", limit=25, offset=0, tag="", type="", model="", provider="", exclude_api=False)	comfy templates ls [--tag/--type/--model/--provider …]	Find a built-in workflow template: free-text query (client-side over name/title/description/tags/models), paged via limit/offset, narrowed by the tag/type/model/provider gallery filters or exclude_api=True. Returns {total, shown, offset, rows:[{name,title,description,output_type,tags,category_title}]}. A row's API tag marks a paid hosted-API template; the gallery often titles its free open-source sibling identically (e.g. two "MiniMax H3: Text to Video" rows), so tags/category_title — never the title — are what tell the two routes apart.
get_template(name, check_local=True)	comfy templates show <name> (+ comfy validate)	Show one template's details/schema before fetching it, plus a local_check block cross-checking its graph against the live object_info of your install — see Templates your install can't run. check_local=False skips the check (metadata only, one call).
fetch_template(name, out_path, check_local=True)	comfy templates fetch <name> --out <path> (+ comfy validate)	Write a template's runnable workflow JSON to out_path; returns {path, local_check} — path is the absolute path for run_workflow, local_check is the same cross-check run on the file just written. The file is written either way.
nodes(action="search", query="", name="", produces="", accepts="", category="", pack="", label="", limit=None, from_type="", to_type="", max_depth=None, max_paths=None)	comfy nodes search/show/ls/upstream/downstream/path/types/categories	One grouped tool over the eight former search_nodes/get_node/list_nodes/nodes_upstream/nodes_downstream/nodes_path/nodes_types/nodes_categories tools — pick a behavior with action. "search" (default) finds a class name by keyword; "get" returns one class's full input/output schema; "list" filters by produces/accepts/category/pack/label (bare call lists all); "upstream"/"downstream" list classes that can feed name's inputs / accept its outputs (limit caps the count); "path" finds node chains routing a value from from_type to to_type (max_depth/max_paths default to 6/10 when omitted); "types" lists every connection type by connectivity; "categories" returns the menu-category tree. Each param is scoped to the actions that consume it — query only "search", name only "get"/"upstream"/"downstream", the five list filters only "list", limit only "upstream"/"downstream", from_type/to_type/max_depth/max_paths only "path" — passing one where the action does not use it is rejected rather than silently ignored. All reads are against the live local object_info (includes installed custom nodes).
workflow_deps(workflow_path)	comfy node deps-in-workflow --workflow <path> --output <tmp>	Which node packs a workflow needs, resolved from the node classes it references — the diagnosis half of the missing-node story, and the only tool here that can go from a class name to a pack id. nodes ("get"/"search") reads the running install's live object_info, so by construction it only ever finds classes you already have; this reads ComfyUI-Manager's node→pack map, which covers packs that are not installed. Returns Manager's manifest verbatim: `{"custom_nodes": {"": {"state": "installed"
node_dependencies(pack="", registry_id="")	comfy node deps [<pack>] [--registry <id>]	A custom node pack's declared Python requirements (its requirements.txt / pyproject.toml) against the versions actually installed in the workspace venv — each requirement carrying a satisfied / mismatch / missing / unparseable / unknown status, plus per-pack counts. This is what tells you whether a pack's imports are failing because a dependency is absent, or whether installing one pack would conflict with another. pack empty reports every installed pack; registry_id pre-checks a not-yet-installed registry pack against the same venv before you install it (its latest published version — the registry exposes no per-version endpoint). The two are additive, so naming the same id both ways yields an installed row and a registry row to compare. Read-only: nothing is installed or changed. Pack-level filesystem + venv introspection, so it is deliberately separate from nodes, which introspects node classes over the live object_info. The verb ships in comfy-cli 1.14.0, this server's floor; on a build without it (one that got past the fail-open version guard) it returns {"error": …, "unsupported": true} rather than a raw usage dump.
search_models(query="", folder="")	comfy models search / models list-folder <folder> / models list-folders	List/search model files on disk. Local: filenames only, no cloud enrichment.
list_partner_models(style="", partner="", query="", limit=100, offset=0)	comfy generate list [--style S] [--partner P] [--query Q]	The catalog of hosted partner models partner_generate can run — the only place that list exists (nothing in discover / nodes / search_templates carries the partner aliases). One record per model: alias (what you pass as model), id, partner, category (the model's style, and the axis style filters on — text-to-image, image-edit, image-to-image, text-to-video, image-to-video, video-extend, controlnet, inpaint, outpaint, upscale, background, lipsync, vectorize as this is written; comfy-cli owns that set, so read it off an unfiltered call), mode (sync/async, the partner's protocol — partner_generate waits either way) and the model's full, untruncated summary. Filters are forwarded to comfy-cli: style is exact and case-sensitive, partner exact and case-insensitive, query a substring over id + summary. limit (default 100, capped at 200) / offset page the result ({total, shown, offset, filters, models}) so a growing catalog can't trip the client's tool-output cap; 52 models as this is written, so the default returns all of them — check shown against total rather than assuming that stays true.
partner_model_schema(model)	comfy generate schema <model>	One partner model's callable parameters — what to put in partner_generate's params. Returns {model, id, partner, category, summary, mode, polling, content_type, params, example}, where each params record carries name, type (string/integer/number/boolean/enum/object/array/binary — binary is a local file path comfy-cli uploads or inlines for you), required, default, enum and the spec's own description. Reads the spec only: no partner call, no key, no spend.

Lifecycle and assets

Tool	Wraps	What it does
launch_comfyui(extra_args=None, confirm_network_exposure=False)	comfy launch --background [-- <extras>]	Start the local ComfyUI detached; forwards extra_args to ComfyUI. Network-exposing flags ask the USER first. ComfyUI has no authentication, so --listen on a non-loopback address — including a bare --listen, which ComfyUI expands to every interface — or --enable-cors-header would publish its full API (arbitrary workflow execution, plus file reads/writes under whichever directories it was started with — the same extra_args can move those roots with --base-directory) to anything that can reach this machine. Those raise an MCP elicitation naming exactly that and echoing the whole argument list, so the user approves the command line that actually runs; a decline starts nothing; on a client that cannot show prompts the call errors unless confirm_network_exposure=True, which an agent may pass only when the user has actually agreed. That prompt is raised even when confirm_network_exposure=True is passed, so a host's "always allow this tool" toggle is not standing authority to publish the machine. --listen 127.0.0.1 / ::1 / localhost is the default bind spelled explicitly and needs no confirmation, and every other flag (--port, --cpu, …) passes straight through unprompted. extra_args is bounded (64 entries, 4096 characters each) so an oversized argv is a named error rather than an OSError from the spawn. Serialized with stop_comfyui / restart_comfyui: they share comfy-cli's one recorded server and the ComfyUI port, so a call made while another lifecycle call is in flight is refused immediately rather than racing it.
stop_comfyui()	comfy stop	Stop the ComfyUI that comfy-cli launched (only its own recorded pid). Shares the launch/restart one-at-a-time lock, so it cannot land between a restart's stop and its launch.
restart_comfyui(extra_args=None, confirm_network_exposure=False, confirm_kill_untracked=False)	comfy stop then comfy launch --background [-- <extras>]	Stop-then-launch the local ComfyUI (best-effort stop); forwards extra_args to the fresh server. Handy for relaunching with different flags — which is why it carries launch_comfyui's network-exposure confirmation unchanged (--listen on a non-loopback address, or --enable-cors-header, asks the USER first). The gate runs before the stop, so a declined restart leaves the running server alone rather than killing it and then refusing to bring it back. When the stop finds nothing recorded and the launch then loses the port, a ComfyUI is running that comfy-cli did not start — so this asks comfy-cli what it is (comfy stop --port <p> --dry-run, which reports the process it would stop without stopping it) and, if the engine positively identifies a ComfyUI, offers to recycle it: the USER is shown that process's pid, command line and port and asked, and only on a yes is it stopped (comfy stop --port <p>) and the launch retried once. Declining, an engine that will not vouch for the listener, and a comfy-cli too old to have comfy stop --port all land on the same port error as before, enriched with whatever identity the dry run did establish. That confirmation necessarily comes mid-sequence, which is safe because the stop half was a no-op — nothing was recorded, so declining leaves the running server untouched. On a client that cannot show prompts the kill needs confirm_kill_untracked=True, which an agent may pass only once the user has actually agreed (the equivalent outside this server is comfy stop --port <p> in a terminal); like every other confirm flag it grants nothing on a client that can be prompted. Sessions pointed at a remote ComfyUI (COMFYUI_URL / COMFYUI_HOST) never reach that path — the lifecycle verbs are local-only, so which machine's port is in question stops being obvious. Both halves run inside one lifecycle slot, so a concurrent launch_comfyui / stop_comfyui is refused rather than slipping into the gap between them (bounded by the timeouts, ~4 minutes worst case, or ~10 if it is waiting on that confirmation — the prompt is raised without dropping the slot).
update_comfyui(target="comfy", confirm_update_all=False)	comfy update <all|comfy|cli>	Update the local install: "comfy" = ComfyUI core, "all" = the installed custom node packs, "cli" = comfy-cli itself. This is what server_info's freshness block points at when it reports a stale install. Slow (a core update re-installs requirements; 30-minute timeout) and the updated code only takes effect after a restart_comfyui. target="all" asks the USER first — and only that target. It git pulls and pip installs every third-party custom node pack into ComfyUI's Python environment, so it runs code those packs' authors have published since you installed them, and it can move a pack (or a shared dependency) to a version other packs and your saved workflows don't work with. comfy-cli does not gate that, so on a client that supports MCP elicitation a prompt naming exactly that is raised and a decline runs nothing; on a client that cannot show prompts the call errors unless confirm_update_all=True, which an agent may pass only when the user has actually agreed. That prompt is raised even when confirm_update_all=True is passed, so a host's "always allow this tool" toggle is not standing authority to run third-party code. target="comfy" and target="cli" update first-party code from known repositories and are never prompted. Any other target is rejected before comfy-cli is invoked (and before anyone is asked), and a second update requested while one is still running is refused rather than run in parallel (concurrent git/pip against one workspace can leave it half-installed) — that refusal comes before the prompt too, so nobody approves a call that was never going to run.
switch_comfyui_version(version, confirm_switch=False)	comfy update comfy --version <version>	Move the local ComfyUI install to a specific version — "nightly", "latest", or a release like "0.24.0" / "v0.24.0" — so you can roll back to reproduce or rule out a regression (update_comfyui only ever moves forward to the latest). Destructive: the engine stashes any uncommitted changes in the ComfyUI checkout, moves it to that version, and reinstalls that version's Python dependencies (minutes, not seconds; 15-minute timeout). The USER is asked to confirm every call — on a client that supports MCP elicitation a prompt naming exactly that is raised, and a decline cancels with nothing changed; on a client that cannot show prompts the call errors unless confirm_switch=True, which an agent may pass only when the user has actually agreed. That prompt is raised even when confirm_switch=True is passed, so a host's "always allow this tool" toggle is not standing authority over the install. It refuses while a local ComfyUI is running (reinstalling under a live process can leave it serving half-replaced code) — checked both before the prompt and again immediately before the switch, since the prompt may sit unanswered for minutes, and fail-closed, so a comfy env this server cannot read is refused rather than read as "stopped" — and it does not restart anything — the flow is stop_comfyui → switch_comfyui_version → launch_comfyui → server_info to confirm what came up. Returns {switched_to, result, restart_required: true}. A malformed version is rejected before comfy-cli is invoked; a comfy-cli whose comfy update predates --version surfaces as an "upgrade comfy-cli" error rather than a raw usage dump; and it shares update_comfyui's one-at-a-time lock.
install_node(names, confirm_install=False)	comfy node install <name...> --exit-on-fail	Install custom node packs into the local ComfyUI — the acquisition half of the missing-node story, after validate_workflow / run_workflow names a node class this install lacks and node_dependencies(registry_id=…) pre-checks the pack's requirements. names are registry pack ids (slugs like "comfyui-impact-pack"), not node class names: a git URL, a filesystem path, or "all" is refused before comfy-cli is invoked — the URL case deliberately, because the confirmation prompt promises the user a named pack from the registry, so nothing else may ride through it. (To update the packs you already have, use update_comfyui(target="all"); to install from a URL, run comfy node install in a terminal.) Installing a pack runs third-party code — a pip install of its dependencies into the ComfyUI environment plus the pack's own install script — so the USER is asked to confirm every call, and that prompt is raised even when confirm_install=True, since a host's "always allow this tool" toggle is not standing authority to execute third-party code and the pack names are frequently a model's guess. On a client that cannot show prompts the call errors unless confirm_install=True, which an agent may pass only once the user has actually agreed. It does not restart anything — new nodes are invisible until ComfyUI restarts, so the flow is install_node → restart_comfyui → nodes(action="search") — and it shares update_comfyui's one-at-a-time lock (same venv, same pip). --exit-on-fail is always forwarded, because without it comfy-cli reports a failed install as success — but it is not sufficient on its own: ComfyUI-Manager prints a pack's failure before consulting the flag, so comfy node install can report a pack as failed and still exit 0. The verdict is therefore read out of the engine's own output rather than off the exit status. 30-minute timeout. Returns {installed, result, restart_required} — installed lists only the packs the engine did not report as failed, not an echo of names — plus {failed, error} when any pack failed, where each failed entry carries the engine's own message and a code of pack_not_found (the id is not in this install's registry channel, so retrying it will not help) or install_failed. restart_required is false when nothing was installed, because there is then nothing for a restart to pick up.
upload_file(paths, overwrite=False)	comfy upload <files...> --overwrite/--no-overwrite	Stage source images/masks into the target ComfyUI's input dir (unlocks img2img / inpaint). Goes to whichever ComfyUI the server targets — the local install by default, or the remote a configured COMFYUI_URL/COMFYUI_HOST names, the same one run_workflow submits to (Driving a remote ComfyUI); remote upload needs comfy-cli ≥ 1.14.0, and an older one raises with the upgrade step instead of staging locally where the remote run cannot see the files. Entries must already exist on this filesystem (they are read here and sent to the target) and should be absolute — comfy-cli runs with the ComfyUI workspace as its working directory, so a relative path resolves against the workspace, not the agent's cwd. For an image the user attached in chat: an MCP server never receives attachment bytes (the protocol has no client-to-server path for them), but several clients save the attachment and put its absolute path in the agent's context — Claude Code injects an [Image: source: <absolute path>] line — and that path is an ordinary local file you can pass straight to paths. If your client gives no path, ask the user to save the file and supply it; that is the portable flow.
download_model(url, relative_path=None, filename=None, wait=True, timeout_seconds=110.0)	comfy model download --url <url> [--relative-path <path>] [--filename <name>] --background	Download a model file by direct URL (HuggingFace / CivitAI) into the local models dir; download-by-URL only, not a hub search. Local-only and enforced: comfy model download has no --host/--port, so with a remote configured (COMFYUI_URL/COMFYUI_HOST) this refuses instead of writing the checkpoint to a disk the remote cannot see — install the model on the remote host itself, or set COMFY_MCP_REMOTE_SHARED_MODELS=1 if this machine's models dir is the remote's (shared NFS / tailnet mount). See Driving a remote ComfyUI. The transfer is submitted to comfy-cli's background worker and returns a download_id, so a multi-GB checkpoint no longer holds the MCP request open past the client's deadline: wait=True (default) polls that id for you within a bounded budget and returns {"timed_out": True, "download_id": …} — not an error — if the transfer is still running, while a failed / cancelled download raises with comfy-cli's own error. On that path timeout_seconds is the end-to-end budget for the whole call, submit included, so the submit and the poll cannot add up past the client deadline the 110s default is chosen to sit under. wait=False returns the submit payload immediately and keeps the submit's own fixed budget. The file is written straight to its final path as it transfers, so a filesystem / search_models check mid-flight sees a present-but-incomplete file — download(action="status") is the source of truth. relative_path resolves from the workspace root and must be the models dir or a subfolder of it — models, models/loras (a bare loras is rejected, not assumed); sibling dirs like custom_nodes/…, input, output are refused. Use / as the separator on every host, Windows included. Against a comfy-cli too old to know --background (anything below 1.14.0, which only reaches here past the fail-open version guard) it falls back to the previous foreground download — which has no id to detach or poll, so it blocks even on wait=False, and every payload it returns is marked background_unsupported: true to say so. On that fallback wait=True is bounded by what is left of your timeout_seconds (capped at 1800s) rather than by a silent half hour: when the bound expires the transfer is killed and the error names where an incomplete file may remain, since there is no download_id to check it with. Cancelling the tool call kills the transfer the same way instead of orphaning it.
download(action="status", download_id="", timeout_seconds=None)	comfy model download-status/download-cancel <download_id>	One grouped tool over the three former download_status/wait_for_download/cancel_download tools — pick a behavior with action. Does not start a transfer — that's download_model, whose download_id this tool consumes. "status" (default) returns status, completed_bytes / total_bytes / percent, elapsed_seconds, dest, and error — the only proof a model is complete and loadable. "wait" polls (bounded, default 25.0s, ceiling 3600s) until a download reaches a terminal state (completed / failed / cancelled), returning a {"timed_out": True, …} payload on expiry — chain several rather than one long call, the job(action="wait") shape, for transfers. "cancel" stops a running download and removes its partial file. download_id is required for every action; timeout_seconds only for "wait" — passing it elsewhere is rejected rather than silently ignored. On a comfy-cli without the verb, returns {"error": …, "unsupported": true} instead of a raw usage dump.

Node introspection (nodes, all eight actions) and search_models read the user's live install (custom nodes included), not a static catalog — that's the local differentiator from the cloud MCP's equivalents. The graph-wiring actions ("upstream" / "downstream" / "path") are what an agent authoring a workflow uses to find compatible nodes. workflow_deps is the one node tool that does NOT read the live install: it resolves a workflow's classes against ComfyUI-Manager's node→pack map, which is what lets it name a pack that is not installed — precisely the question the live-catalog tool cannot answer. node_dependencies reads that same live install from the other side — the packs on disk and the venv they installed into, rather than the node classes ComfyUI loaded from them — which is how an agent tells "this pack's nodes are missing from object_info" apart from "this pack's Python dependencies never installed".

Troubleshooting

macOS: PermissionError: [Errno 1] Operation not permitted / Fatal Python error

Symptom. Setup fails with a raw Python startup crash naming a file under ~/Documents, ~/Desktop or ~/Downloads — most often the ComfyUI venv's pyvenv.cfg:

Fatal Python error: init_import_site: Failed to import the site module
PermissionError: [Errno 1] Operation not permitted: '/Users/you/Documents/ComfyUI/venv/pyvenv.cfg'

Cause. macOS protects those three folders with TCC (Transparency, Consent & Control). An app without Full Disk Access cannot read them — and neither can the processes it spawns. So when your ComfyUI install (and its venv) lives under one of them, the comfy binary your MCP client launches dies before it executes a single line. Nothing is wrong with ComfyUI, comfy-cli, or this server: it is a macOS privacy setting.

Fix — either one works:

1. Grant your MCP client Full Disk Access. System Settings → Privacy & Security → Full Disk Access → add the app (Claude Desktop, Cursor, or the terminal you launch the client from), then quit and reopen it so the new permission takes effect.
2. Or move the ComfyUI folder somewhere unprotected — e.g. ~/ComfyUI — and re-point comfy-cli at it with comfy set-default <path>. Update COMFY_BIN in your client config too if it names a path inside the old location.

Where it can, the server says this for you: a tool call blocked this way returns the guidance above instead of the raw traceback. The one case it cannot catch is its own interpreter startup (this server installed under a protected folder) — Python dies before any of its code runs, so that one surfaces as the raw traceback in your client's MCP logs. Same fix.

Failure log (opt-in)

When you're diagnosing a flaky setup, an MCP client's transcript is a poor record: it scrolls, it truncates, and the interesting failures (a missing comfy binary, a crash before any JSON, a timeout) are exactly the ones that leave the least behind. Set COMFY_MCP_DEBUG_LOG and the server appends one JSON object per comfy-cli failure to a local file you can jq, grep, or zip up and attach to a bug report.

Value	Behavior
unset, empty, or 0	Off (the default). Nothing is created and no log file is opened.
1	On, at the default path for your OS (below).
anything else	On, and the value is used as the log file path (parent directories are created).

Default paths — the same per-OS local-state convention comfy-cli itself uses:

OS	Path
macOS	~/Library/Application Support/comfy-mcp/failures.jsonl
Windows	~/AppData/Local/comfy-mcp/failures.jsonl
Linux / other	~/.config/comfy-mcp/failures.jsonl

Each line records the failure kind (error_envelope, no_json, timeout, binary_missing, schema_mismatch), a UTC ts, the comfy-cli args, its exit_code and the envelope's error_code, the message you saw in your client, and up to 4,000 characters of stdout_tail / stderr_tail — deliberately more output than an error message can carry:

$ COMFY_MCP_DEBUG_LOG=1 …            # in your MCP client config's env block
$ jq -r 'select(.kind == "timeout") | .ts + "  " + (.args | join(" "))' \
    ~/Library/Application\ Support/comfy-mcp/failures.jsonl

The file rotates itself: 1 MiB per file with two older generations kept (failures.jsonl.1, failures.jsonl.2), so it stops growing at roughly 3 MiB no matter how long you leave it on. Successful calls are never recorded, and nothing is ever transmitted anywhere — the log is local, full stop.

Privacy — review before sharing. The log contains local file paths and comfy-cli's own command output, which can include the workflow or prompt text comfy-cli echoed back. Credentials in a URL are masked (user:pass@ userinfo, and the whole query string, are stripped) wherever the URL appears — in args, in message, and in the stdout_tail / stderr_tail captures — but read a file over before you attach it to an issue. The log directory is created 0700 and its files 0600, so on a shared machine they are readable only by you.

Smoke test

Turn the manual validation ritual into one command. The e2e smoke test drives the real tools end-to-end (no mocks): server_info → run_workflow on a checkpoint-free EmptyImage → SaveImage graph → fetch_outputs, and asserts a valid PNG lands in a temp out_dir.

./scripts/smoke.sh            # or: python -m pytest tests/e2e -m e2e

It needs a running local ComfyUI (COMFYUI_URL, default http://127.0.0.1:8188) and the comfy binary on PATH (or COMFY_BIN). Without both it skips rather than fails. The e2e tests are deselected by default from plain pytest runs, so it's safe to run anywhere — and the pytest gate stays green on CI runners that have neither.

Contributing

Contributions are welcome. See CONTRIBUTING.md for dev setup (pip install -e '.[dev]', pytest, ruff) and the thin-wrapper architecture rule, and AGENTS.md for the full guidelines. This project follows a Code of Conduct. To report a vulnerability, see SECURITY.md.

License

Comfy MCP is dual-licensed (see LICENSE and NOTICE):

• GNU Affero General Public License v3.0 or later — free for use under the AGPL's terms, including the network-use source-disclosure obligation in section 13.
• Commercial license — for use in proprietary products or hosted services without AGPL obligations. Contact licensing@comfy.org.

It wraps the GPL-3.0 comfy-cli by shelling out to the comfy binary as a separate process — no GPL code is imported or linked. comfy-cli remains GPL-3.0-licensed and is distributed separately; how its copyleft applies depends on how the programs interact.

© Comfy Org.

Trademarks

"Comfy," "ComfyUI," and the Comfy Org name and logos — including the mark in assets/logo.svg — are trademarks of Comfy Org. The AGPL is a copyright license and grants no rights to use those names or logos; the commercial license grants none either unless it says so in writing. Forks and derivative works are welcome under the license, but must not be named or branded in a way that suggests they are official Comfy Org software or carry Comfy Org's endorsement.

Accurate, descriptive references — tutorials, reviews, integrations — are welcome. See the brand guidelines for the full rules and how to request permission beyond them.