maginary-mcp

Model Context Protocol server for Maginary — enumerate the prompt-DSL flags the engine accepts, kick off generations, and poll for results, all from inside your MCP-compatible client (Claude Desktop, Cursor, Continue, custom).

why

Maginary uses a Midjourney-style --flag prompt DSL over an async HTTP API. This server:

• surfaces the full parameter catalog to your LLM so it can pick the right flags
• offers a one-shot generate tool that hits POST /api/gens/
• offers get_generation + wait_for_generation for polling to a terminal state
• works offline for the catalog tools (ships a bundled snapshot; refreshed from the live docs endpoint at startup when reachable)

install

uvx maginary-mcp                   # ephemeral run via uv
# — or —
pip install maginary-mcp
maginary-mcp

Requires Python 3.10+.

configuration

Environment variables:

Claude Desktop config

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or the equivalent on your OS:

{
  "mcpServers": {
    "maginary": {
      "command": "uvx",
      "args": ["maginary-mcp"],
      "env": {
        "MAGINARY_API_KEY": "sk-mag-…"
      }
    }
  }
}

hosted (no-install) — Streamable HTTP

Connect a client straight to the hosted server at https://mcp.maginary.ai/mcp. Zero install — the server is multi-tenant, so each request is scoped to whatever credential it arrives with. Two ways to authenticate, pick whichever fits the client:

Connect (OAuth) — for Claude Desktop, claude.ai, and any other client that speaks MCP's OAuth spec. Add the server with no headers at all:

{
  "mcpServers": {
    "maginary": { "url": "https://mcp.maginary.ai/mcp" }
  }
}

Click "Connect" in the client. It opens a login page on app.maginary.ai, you sign in and approve the requested scopes, and the client holds the token from then on — no key to generate or paste. Requires the server to be running with MAGINARY_MCP_REQUIRE_AUTH=1; without it, no login is asked for at all.

API key — for any client that doesn't do the OAuth dance (or if you'd rather not click through a login), generate a key at app.maginary.ai/dashboard#api-keys and send it yourself:

{
  "mcpServers": {
    "maginary": {
      "url": "https://mcp.maginary.ai/mcp",
      "headers": { "Authorization": "Bearer sk-mag-…" }
    }
  }
}

Both are equivalent once connected — same tools, same account. Catalog tools work with no credential either way; generate / get_generation / wait_for_generation need one. Run the hosted server yourself with:

paying inside the tool call (x402 over MCP)

No key at all? Call generate anyway. Out of credits (or no account), the result is isError: true with the x402 PaymentRequired at the top level (accepts, resource, …) plus error: "payment_required". An x402-capable MCP client — the x402 SDK's x402MCPSession — signs accepts[0] and calls the same tool again with the payment in _meta["x402/payment"]. The server forwards it to the backend as PAYMENT-SIGNATURE; the backend verifies, settles on Base and, for a wallet with no account, creates one. The settled result carries the on-chain receipt in _meta["x402/payment-response"] and x402_receipt, and a first settlement returns x402_account: {api_key, wallet}. Pass that key as _meta["maginary/api_key"] on later calls (polling needs it), or open a new connection with it as the Bearer header. The server holds no payment logic; everything is decided by the backend's /api/gens/ contract.

lost the key? recover it, no new payment

A key returned by x402_account is shown exactly once. If it's gone — the agent never persisted it, or a human never wrote it down — paying again from the same wallet does not hand back a second one: repeat payments just add credits to the account. That's deliberate (an unbounded stream of fresh keys from routine top-ups would be a bigger secret-exposure surface than losing one, and would remove any reason to persist a key at all), so recovery is a separate, explicit step: prove you hold the private key by signing a short message, and the backend reissues a key.

POST https://app.maginary.ai/api/auth/x402/recover-key/
{
  "address": "0xYourWalletAddress",
  "timestamp": 1741000000,
  "signature": "0x..."
}

signature is a standard personal_sign (EIP-191 — the same call MetaMask, ethers' signer.signMessage(str), or eth_account's Account.sign_message already expose) over the literal string:

Maginary: issue a new API key for <address> at <timestamp>. This does not move funds.

with <address> lowercased and <timestamp> the same unix seconds sent in the body. The timestamp must be within 5 minutes of the server's clock (30 s of future skew tolerated) — it's the only replay defense, so a stale or reused signature is rejected the same as a wrong one. A 200 revokes every existing key on the account and returns exactly one fresh one, in the body and in X-Maginary-Api-Key — same shape as x402_account, so code that already handles the first-payment response handles this response too.

This is a plain backend REST call, not an MCP tool — deliberately, for the same reason the payment logic itself lives in the backend and not here: the server holds no identity logic of its own, and any agent that can already construct and sign the x402 payment above can construct and sign this one the same way. The one place this needs to be discoverable from inside an MCP session is the 402 itself: an anonymous generate call always comes back payment_required before the backend has any idea which wallet is asking, so its error text always names this endpoint alongside the payment instructions — an agent that gets stuck here learns about it from the exact same message it already parses to learn about paying in the first place, no separate discovery step.

pip install "maginary-mcp[http]"
maginary-mcp-http          # serves /mcp on 0.0.0.0:8642 (MAGINARY_MCP_PORT to change)
# — or —
docker build -t maginary-mcp . && docker run -p 8642:8642 maginary-mcp

The hosted server sets no MAGINARY_API_KEY (keys come per-request). Extra env: MAGINARY_MCP_HOST (default 0.0.0.0), MAGINARY_MCP_PORT (default 8642).

Claude Skill

The server ships an Agent Skill that teaches the --flag DSL, model selection, and the async generate→poll flow:

maginary-mcp --install-skill   # -> ~/.claude/skills/maginary-image-gen/SKILL.md

The skill stands on its own — hosts without MCP get the DSL plus the raw REST calls (POST /gens/ → poll). With the server connected, Claude instead calls search_parameters for the authoritative flag list and generate/wait_for_generation natively. Re-running updates it; local edits are protected unless you pass --force. Source: src/maginary_mcp/SKILL.md.

tools

catalog (no auth)

• list_parameters(category?, status?, include_reserved=false) — enumerate the catalog
• search_parameters(query, category?, include_reserved=false) — text search over names / aliases / desc / examples
• get_parameter(name) — full record for one flag (canonical name or alias)

list_parameters responses include the categories / statuses taxonomy, and both list/search responses carry source (live vs bundled-snapshot).

generation (auth required)

• generate(prompt, callback_url?) — POST /api/gens/
• get_generation(uuid) — GET /api/gens/{uuid}/
• wait_for_generation(uuid, timeout_s=45) — poll to done / failed; a timeout result means still running — call again

worked example

Inside an MCP-capable client, once configured:

"Search the maginary catalog for anything about aspect ratio."

The LLM calls search_parameters("aspect") and gets back the --ar entry with values, examples, and supported models.

"Now generate a cinematic portrait 16:9 with the flagship model."

The LLM calls generate("a cinematic portrait --ar 16:9 --flagship"), gets a uuid, then wait_for_generation(uuid) and reads image_urls[] out of the terminal record.

catalog freshness

• Live fetch on startup from https://maginary.ai/docs/parameters.json, 5-second timeout.
• Bundled snapshot at src/maginary_mcp/parameters_snapshot.json used as a fallback whenever live fetch fails (no network, docs site down, etc.).
• The snapshot is refreshed manually by the maintainer via python scripts/refresh_snapshot.py — deliberately not baked into the wheel build so a new snapshot always corresponds to a reviewed commit.

The source field on list_parameters / search_parameters responses tells you which one is active.

development

cd mcp
python -m venv venv && source venv/bin/activate
pip install -e .
maginary-mcp   # runs on stdio; kill with Ctrl+D

license

MIT.