dcc-mcp-core 0.18.35

Foundational library for the DCC Model Context Protocol (MCP) ecosystem

dcc-mcp-core

中文 | English

Agent-first DCC control plane: one CLI, one gateway, every live creative host.

dcc-mcp-core turns Maya, Blender, Houdini, Photoshop, and custom studio tools into discoverable, routable MCP endpoints. Agents stop guessing from shell output and start working with live scene state, scoped tool catalogs, structured results, viewport diagnostics, audit logs, and workflows that can survive real production constraints.

The default operator path is dcc-mcp-cli: local agent-control commands ensure the loopback gateway is available for Admin UI and IDE MCP clients, then use live DCC sessions from the shared FileRegistry and each selected instance's direct MCP endpoint; remote profiles route through a selected gateway. Endpoint/admin/update commands also ensure the local gateway when needed, so agents and CI scripts do not need a fragile preflight dance. The same stack powers the browser Admin UI, marketplace skill installs, package updates, Sentry/webhook/OTLP integration settings, and evidence panels for traces, calls, logs, and runtime health.

Under the hood it combines MCP 2025-03-26 Streamable HTTP, a zero-code Skills system built on agentskills.io 1.0, and a Rust gateway for discovery, routing, installation, linting, updates, and operations. The Python package keeps zero third-party Python library dependencies for embedded DCC hosts and depends on the companion dcc-mcp-server wheel so daemon-backed gateway startup has a packaged binary even when PATH is empty. Standalone dcc-mcp-cli and dcc-mcp-server binaries also ship through GitHub Releases for workstation-style installs. Supports Python 3.7–3.14.

---

What You Get

Need	dcc-mcp-core gives you
Let agents operate real DCC sessions	MCP + REST endpoints for Maya, Blender, Houdini, Photoshop, and custom hosts
Keep tool context small	CLI discovery: search -> describe, then call; no giant first-page tools/list scrape
Start reliably from an agent shell	dcc-mcp-cli list/search/describe/call auto-ensure the local gateway, then use local registry + direct MCP or remote gateway profiles
Add and update tools without framework glue	SKILL.md + sibling YAML/scripts, marketplace install/update, aligned with agentskills.io
Debug live workstation state	Admin UI, viewport diagnostics, audit logs, traces, logs, metrics, Sentry/webhook integration state
Survive production constraints	Main-thread dispatch, async jobs, sidecar/server binaries, workflow and artefact primitives

Product Surfaces

Surface	What operators see	Why it matters
dcc-mcp-cli	health, list, search, describe, call, load-skill, reload-skills, marketplace, and update commands	Agent and CI entry point; local DCC control works from registry defaults, remote control works through gateway profiles
Gateway Admin UI	Instances, server versions, one-click update actions, skill paths, marketplace packages, integrations, calls, traces, logs, and health	One browser surface for live workstation operations
Skills Marketplace	Catalog search, install, uninstall, outdated checks, and package updates	Teams can distribute DCC capabilities without rebuilding adapters
Integrations	Sentry DSN, webhook config, WeCom message push, and OTLP endpoint visibility with pending-restart state	Observability settings are editable, masked, and backed by real gateway APIs

Runtime Architecture

Use the process names this way:

• DCC startup hook runs inside Maya, Houdini, 3ds Max, or another host and should only launch the service path without blocking the UI/main thread.
• Per-DCC service is one registered runtime row for one concrete DCC instance.
• Sidecar is the dcc-mcp-sidecar child launched by dcc-mcp-server sidecar; it bridges host RPC to MCP/REST and watches the DCC process.
• Gateway daemon is the one machine-wide routing/Admin process.
• Guardian is the live service loop that probes gateway /health and re-ensures the daemon through gateway-launch.lock.
• Service heartbeat keeps registry rows fresh; it is not the gateway restart trigger.

The intended plugin experience is: open DCC -> startup hook launches a per-DCC service/sidecar -> that service ensures the machine-wide gateway daemon exists -> it registers and heartbeats one instance row -> the gateway routes across every live DCC instance.

Why This Matters

Generic MCP servers and CLI wrappers expose commands. dcc-mcp-core exposes a live DCC control plane built for production sessions:

• Agents can reason from active scenes, documents, selections, viewport captures, output streams, and host-published resources instead of blind shell output.
• Progressive discovery keeps context small: search compact capability records first, inspect only the selected schema, then load or call the chosen tool.
• One gateway can route across many DCC instances, versions, scenes, and custom studio hosts without merging every backend action into one huge tools/list.
• Main-thread dispatch, readiness probes, async jobs, cancellation, persistence, and artefact hand-off match the constraints of embedded desktop hosts.
• Skills are packages: SKILL.md, tools.yaml, scripts, reference docs, and Rez/context bundles can travel through normal studio distribution workflows.
• Audit logs, security annotations, diagnostics, telemetry, and Admin UI panels give operators enough evidence to trust what agents did.

Recommended Agent Workflow

1. Start from the CLI path when the agent can run shell: use the bundled dcc-cli-gateway skill, then run dcc-mcp-cli list for local inventory or dcc-mcp-cli list --gateway <profile> for a remote workstation.
2. Search compactly with dcc-mcp-cli search; local mode talks directly to the registered DCC MCP endpoint, while remote profiles route through the selected gateway.
3. Inspect before loading or calling with dcc-mcp-cli describe <tool_slug>. Load only what the task needs with dcc-mcp-cli load-skill when the selected tool depends on an unloaded skill.
4. Call the typed tool with dcc-mcp-cli call, then inspect structured results, job updates, resources, prompts, diagnostics, and follow-up hints.
5. Use marketplace commands to search, install, and update community or studio skill packages; use IDE MCP only when the host already has an MCP connector configured.

tools/list is MCP-compatible and paginated. Treat it as a transport listing, not as a complete search index; never assume the first page contains every loaded or discoverable tool.

Quick Start

Install the standalone CLI

Use the release binary when you want the operator/CI control plane without a Python environment:

# Linux/macOS
curl -fsSL https://raw.githubusercontent.com/dcc-mcp/dcc-mcp-core/main/scripts/install-cli.sh | bash

# Windows PowerShell
powershell -c "irm https://raw.githubusercontent.com/dcc-mcp/dcc-mcp-core/main/scripts/install-cli.ps1 | iex"

After install:

dcc-mcp-cli list
dcc-mcp-cli doctor
dcc-mcp-cli search --query "create sphere" --dcc-type maya --limit 20
dcc-mcp-cli describe <tool_slug>
dcc-mcp-cli call <tool_slug> --json '{"radius":2.0}'
dcc-mcp-cli marketplace search --query rigging --dcc maya --limit 20
dcc-mcp-cli health
dcc-mcp-cli update check --binary dcc-mcp-server --current-version <server_version>

Default operator flow:

1. Run dcc-mcp-cli list first for local inventory. It auto-ensures the machine-wide loopback gateway, then reads the local FileRegistry. Register remote machines with dcc-mcp-cli gateway register https://host:19293 --name pcA, then use dcc-mcp-cli gateway list, dcc-mcp-cli list --gateway pcA, or dcc-mcp-cli gateway set pcA. Agent-control commands (list, search, describe, call, load-skill, wait-ready, reload-skills, and stop-instance) plus endpoint/admin/update commands auto-start only loopback gateway targets when needed; pass --no-auto-gateway for a single no-launch invocation. If startup state is ambiguous, dcc-mcp-cli doctor reports the selected profile, registry path/inventory, gateway daemon status, and server binary diagnostics without starting or downloading services.
2. If list returns live instances, use search -> describe -> call; in the local profile the CLI talks to the selected instance's MCP endpoint directly. Keep tools/list as a compatibility listing, not the primary discovery surface.
3. Open http://127.0.0.1:9765/admin for browser operations: instance health, server-version checks, one-click server update staging, skill paths, marketplace package updates, integrations, traces, logs, and token activity.
4. Use the Instances panel update button to stage dcc-mcp-server updates for a running backend. Use dcc-mcp-cli update apply only for the CLI binary itself.

Once any gateway-backed command succeeds, the Admin UI is available at http://127.0.0.1:9765/admin by default. The CLI can be pointed at another gateway with --base-url or DCC_MCP_BASE_URL.

Install the Python core

pip install dcc-mcp-core

Or build from source with the repo's canonical feature set:

git clone https://github.com/dcc-mcp/dcc-mcp-core.git
cd dcc-mcp-core
vx just dev

Serve a DCC over MCP — Skills-First

create_skill_server wires up progressive discovery, skill loading, routing, and structured results:

from dcc_mcp_core import create_skill_server, McpHttpConfig

server = create_skill_server("maya", McpHttpConfig(port=8765))
handle = server.start()
print(handle.mcp_url())   # "http://127.0.0.1:8765/mcp"

Agents then search compactly before they load or call tools. On a direct per-DCC server, use search_tools for active tools, search_skills for unloaded skill candidates, get_skill_info for schema inspection, then load_skill and tools/call. Through the gateway, use MCP search -> describe -> load_skill if needed -> call, or the REST twin POST /v1/search -> /v1/describe -> /v1/call.

---

The Problem & Our Solution

Why Not Just Use CLI?

CLI tools are blind to DCC state. They can't see the active scene, selected objects, or viewport context. They execute in isolation, forcing the AI to:

• Make multiple roundtrips to gather context
• Rebuild state from CLI outputs (fragile, slow)
• Lack visual feedback from the viewport
• Scale poorly with context explosion as requests grow

Why MCP (Model Context Protocol)?

MCP is AI-native, but stock MCP lacks two critical capabilities for DCC automation:

1. Context Explosion — MCP has no mechanism to scope tools to specific sessions or instances, causing request bloat with multi-DCC setups.
2. No Lifecycle Control — Can't discover instance state (active scene, documents, process health) or control startup/shutdown.

Our Approach: MCP + Skills System

We reuse and extend the existing MCP ecosystem, adding:

Capability	Benefit
Gateway Election & Version Awareness	Multi-instance load balancing; automatic handoff when a newer DCC launches
Session Isolation	Each AI session talks to its own DCC instance; prevents context bleeding
Skills System (Zero-Code)	Define tools as SKILL.md + sibling YAML/scripts — no Python glue code needed
Progressive Discovery	Scope tools by DCC type, instance, scene, product; prevents context explosion
Instance Tracking	Know active documents, PIDs, display names; enable smart routing
Structured Results	Every tool returns (success, message, context, prompt) for AI reasoning
Workflow Primitive	Declarative multi-step workflows with retry / timeout / idempotency / approval gates
Artefact Hand-off	Content-addressed (SHA-256) file passing between tools and workflow steps
Job Lifecycle + SSE	tools/call opt-in async dispatch, $/dcc.jobUpdated notifications, SQLite persistence

This isn't reinventing MCP — it's solving MCP's blind spots for desktop automation.

For production pipelines, skills can be distributed as Rez packages and composed into context bundles before a DCC starts. A resolved launch context sets DCC_MCP_* environment variables for project, task, asset, provenance, and skill paths; the adapter records those values in gateway metadata so clients discover only the active project/task/asset surface instead of every studio tool. See Context Bundles and Rez Skill Packages.

---

Why dcc-mcp-core Over Alternatives?

Aspect	dcc-mcp-core	Generic MCP	CLI Tools	Browser Extensions
DCC State Awareness	Scenes, docs, instance IDs	No	No	Partial
Multi-Instance Support	Gateway election + session isolation	Single endpoint	No	No
Context Scoping	By DCC / scene / product	Global tools	No	Limited
Zero-Code Tools	SKILL.md + sibling files	Full Python required	Scripts only	No
Performance	Rust + zero-copy + IPC	Python overhead	Process overhead	Network overhead
Security	Sandbox + audit log	Manual	Manual	None
Cross-Platform	Windows / macOS / Linux	Yes	Limited	Browser only

AI-friendly docs: AGENTS.md · docs/guide/agents-reference.md · .agents/skills/dcc-mcp-core/SKILL.md

---

Architecture: The Current Stack

Gateway Admin UI

The elected gateway ships with a built-in admin console for operators who need to inspect live DCC sessions, server versions, routing health, audit calls, traces, logs, skill paths, marketplace packages, one-click update actions, integration settings, and token activity without leaving the browser. The examples below use representative demo data to show the range of panels available in a busy multi-DCC workstation.

Admin highlights:

• Command Center: separates agent prompt handoff from human CLI recipes, so agents get a concise search -> describe -> call path while operators still have copy-ready dcc-mcp-cli commands. Local instance-control commands use the FileRegistry and direct MCP by default; gateway-backed endpoint/admin commands can still auto-ensure the local gateway when needed.
• Instances: row-based live/stale/unhealthy inventory with server version, adapter version, dispatch readiness, one-click update checks, direct update actions, and restart-required status after staging.
• Skills and Marketplace: list-first skill inventory, custom skill paths, loaded skill details, marketplace browse/installed/source tabs, force reinstall, package updates, and API-backed error messages when a package endpoint returns HTML instead of JSON.
• Integrations: Sentry, webhooks, WeCom message push, and OTLP settings backed by gateway APIs, with editable local config under ~/dcc-mcp/etc and clear pending-restart state when the server must reload startup integrations. WeCom templates can interpolate event fields such as $event, $dcc-type, $tool-slug, and $url.
• Evidence panels: calls, traces, logs, stats, health views, and a contribution-calendar-style token activity heatmap for debugging real agent activity.

The browser UI is backed by the same Admin API used by tests and automation:

Surface	Backing API
Instances and updates	GET /admin/api/instances, POST /admin/api/instances/{id}/update
Skills and marketplace	GET /admin/api/skill-paths, /admin/api/marketplace/*
Integrations	GET /admin/api/integrations, PUT /admin/api/integrations
Analytics and heatmaps	GET /admin/api/analytics/overview, /analytics/timeseries, /analytics/heatmap, /analytics/export
Evidence	GET /admin/api/calls, /traces, /logs, /health

---

Installation Details & Manual API Example

Install the standalone CLI

Use the release binary when you want the operator/CI control plane without a Python environment:

# Linux/macOS
curl -fsSL https://raw.githubusercontent.com/dcc-mcp/dcc-mcp-core/main/scripts/install-cli.sh | bash

# Windows PowerShell
powershell -c "irm https://raw.githubusercontent.com/dcc-mcp/dcc-mcp-core/main/scripts/install-cli.ps1 | iex"

By default, the installers download the latest GitHub Release asset:

Platform	Asset
Linux x86_64	dcc-mcp-cli-linux-x86_64
Windows x86_64	dcc-mcp-cli-windows-x86_64.exe
macOS universal2	dcc-mcp-cli-macos-universal2

For server deployments, each GitHub Release also attaches a ready-to-unpack bundle named dcc-mcp-server-<version>-<platform>.zip. The zip contains both dcc-mcp-server and dcc-mcp-cli at its root (.exe on Windows), so operators can place one archive on a machine and wire both the gateway daemon and control plane CLI into PATH.

Pin a release or install somewhere custom:

export DCC_MCP_VERSION=v0.x.y
export DCC_MCP_INSTALL_DIR="$HOME/bin"
curl -fsSL https://raw.githubusercontent.com/dcc-mcp/dcc-mcp-core/main/scripts/install-cli.sh | bash

$env:DCC_MCP_VERSION = "v0.x.y"
$env:DCC_MCP_INSTALL_DIR = "$env:USERPROFILE\bin"
irm https://raw.githubusercontent.com/dcc-mcp/dcc-mcp-core/main/scripts/install-cli.ps1 | iex

After install:

dcc-mcp-cli health
dcc-mcp-cli list
dcc-mcp-cli search --query "create sphere" --dcc-type maya --limit 20
dcc-mcp-cli describe <tool_slug>
dcc-mcp-cli call <tool_slug> --json '{"radius":2.0}'
dcc-mcp-cli load-skill workflow --dcc-type 3dsmax --instance-id 80321760
dcc-mcp-cli marketplace install <package_name> --dcc maya
dcc-mcp-cli reload-skills --dcc-type maya
dcc-mcp-cli update check --binary dcc-mcp-server --current-version <server_version>
dcc-mcp-cli lint path/to/skills

The default browser control plane is then http://127.0.0.1:9765/admin. Use --base-url or DCC_MCP_BASE_URL when the gateway runs elsewhere.

Install the Python core

# From PyPI (pre-built wheels for Python 3.7+)
pip install dcc-mcp-core

# Or from source (requires Rust 1.95+)
git clone https://github.com/dcc-mcp/dcc-mcp-core.git
cd dcc-mcp-core
vx just dev           # recommended — runs `maturin develop` with canonical features

Every release attaches raw dcc-mcp-cli and dcc-mcp-server binaries for Linux, Windows, and macOS universal2, plus dcc-mcp-server-<version>-<platform>.zip bundles containing both binaries. dcc-mcp-server also ships as the dcc-mcp-server Python wheel for hosts that prefer pip install.

Serve a DCC over MCP — Skills-First (recommended)

create_skill_server wires up the full Skills-First entry point: tools/list returns a paginated transport list with discovery/lifecycle tools plus one stub per unloaded skill. Agents should not scrape only page one. Use search_tools or search_skills to find candidates, get_skill_info to inspect selected schemas, then load_skill to activate only the tools the task needs.

from dcc_mcp_core import create_skill_server, McpHttpConfig

server = create_skill_server(
    "maya",
    McpHttpConfig(port=8765),
)
handle = server.start()
print(handle.mcp_url())   # "http://127.0.0.1:8765/mcp"
# ... later ...
handle.shutdown()

Low-level: register tools manually

import json
from dcc_mcp_core import (
    ToolRegistry, ToolDispatcher, EventBus,
    McpHttpServer, McpHttpConfig,
    success_result, scan_and_load,
)

skills, skipped = scan_and_load(dcc_name="maya")
print(f"Loaded {len(skills)} skills, skipped {len(skipped)}")

registry = ToolRegistry()
registry.register(
    name="get_scene",
    description="Return the active Maya scene path",
    category="scene",
    dcc="maya",
    version="1.0.0",
)

dispatcher = ToolDispatcher(registry)
dispatcher.register_handler(
    "get_scene",
    lambda params: success_result("OK", path="/proj/shots/sh010.ma").to_dict(),
)

# Optional: observe lifecycle events
bus = EventBus()
bus.subscribe("action.after_execute", lambda **kw: print(f"done: {kw['action_name']}"))

result = dispatcher.dispatch("get_scene", json.dumps({}))
print(result["output"])   # {"success": True, "message": "OK", "context": {"path": ...}}

# Expose registry over MCP (register ALL handlers before .start())
server = McpHttpServer(registry, McpHttpConfig(port=8765))
handle = server.start()

---

Core Concepts

ToolResult — Structured Results for AI

All skill execution results use ToolResult, designed to be AI-friendly with structured context and follow-up guidance.

from dcc_mcp_core import ToolResult, success_result, error_result

# Factory functions (recommended). Extra kwargs land in `context`.
ok = success_result(
    "Sphere created",
    prompt="Consider adding materials or adjusting UVs",
    object_name="sphere1",
    position=[0, 1, 0],
)
# ok.context == {"object_name": "sphere1", "position": [0, 1, 0]}

err = error_result(
    "Failed to create sphere",
    "Radius must be positive",
)

# Direct construction
result = ToolResult(
    success=True,
    message="Operation completed",
    context={"key": "value"},
)

result.success   # bool
result.message   # str
result.prompt    # Optional[str] — AI next-step suggestion
result.error     # Optional[str] — error details
result.context   # dict — arbitrary structured data
result.to_json() # JSON-safe serialization for transport

ToolRegistry & Dispatcher

import json
from dcc_mcp_core import ToolRegistry, ToolDispatcher, EventBus

registry = ToolRegistry()
registry.register(name="my_tool", description="My tool", category="tools", version="1.0.0")

dispatcher = ToolDispatcher(registry)
dispatcher.register_handler("my_tool", lambda params: {"done": True})

result = dispatcher.dispatch("my_tool", json.dumps({}))
# result == {"action": "my_tool", "output": {"done": True}, "validation_skipped": True}

bus = EventBus()
sub_id = bus.subscribe("action.before_execute", lambda **kw: print(f"before: {kw}"))
bus.publish("action.before_execute", action_name="test")
bus.unsubscribe("action.before_execute", sub_id)

---

Skills System — Zero-Code MCP Tool Registration

The Skills system lets you register any script (Python, MEL, MaxScript, Batch, Shell, PowerShell, JavaScript, TypeScript) as an MCP tool with zero Python glue code. Aligned with the agentskills.io 1.0 specification.

Architectural Rule — Sibling-File Pattern (v0.15+)

Every dcc-mcp-core extension — tools, groups, workflows, prompts, next-tools, etc. — lives in a sibling file pointed at by a metadata.dcc-mcp.<feature> key. The SKILL.md frontmatter itself only carries the six standard agentskills.io fields (name, description, license, compatibility, metadata, allowed-tools).

my-automation/
├── SKILL.md                      # frontmatter + human-readable body
├── tools.yaml                    # tool definitions + annotations + groups
├── workflows/
│   └── vendor_intake.workflow.yaml
├── prompts/
│   └── review_scene.prompt.yaml
└── scripts/
    ├── cleanup.py
    └── publish.sh

Five Minutes to Your First Skill

1. Create maya-cleanup/SKILL.md:

---
name: maya-cleanup
description: >-
  Domain skill — Scene optimisation and cleanup tools for Maya.
  Not for authoring new geometry — use maya-geometry for that.
license: MIT
compatibility: "Maya 2024+, Python 3.7+"
metadata:
  dcc-mcp:
    layer: domain
    dcc: maya
    tools: tools.yaml
    search-hint: "cleanup, optimise, unused nodes"
    depends: [dcc-diagnostics]
---
# Maya Scene Cleanup

Automated tools for optimising and validating Maya scenes.

2. Create maya-cleanup/tools.yaml:

tools:
  - name: cleanup
    description: "Remove unused nodes from the active scene."
    source_file: scripts/cleanup.py
    execution: sync
    affinity: main
    annotations:
      read_only_hint: false
      destructive_hint: true
      idempotent_hint: true
    next-tools:
      on-success: [maya_cleanup__validate]
      on-failure: [dcc_diagnostics__screenshot, dcc_diagnostics__audit_log]

  - name: validate
    description: "Validate scene integrity after cleanup."
    source_file: scripts/validate.mel
    execution: sync
    affinity: main
    annotations:
      read_only_hint: true

3. Create maya-cleanup/scripts/cleanup.py:

#!/usr/bin/env python
"""Clean unused nodes from the scene."""
from __future__ import annotations

import json
import sys


def main() -> int:
    result = {"success": True, "message": "Cleaned up 42 unused nodes"}
    print(json.dumps(result))
    return 0


if __name__ == "__main__":
    sys.exit(main())

4. Register and call:

import os
os.environ["DCC_MCP_SKILL_PATHS"] = "/path/to/maya-cleanup/.."

from dcc_mcp_core import create_skill_server, McpHttpConfig

server = create_skill_server("maya", McpHttpConfig(port=8765))
handle = server.start()
# Agent calls search_skills("cleanup") → load_skill("maya-cleanup") → maya_cleanup__cleanup

That's it — no Python glue code, just SKILL.md + tools.yaml + scripts.

Supported Script Types

Extension	Type	Execution
.py	Python	subprocess with system Python
.mel	MEL (Maya)	Via DCC adapter
.ms	MaxScript	Via DCC adapter
.bat, .cmd	Batch	cmd /c
.sh, .bash	bashell	bash
.ps1	PowerShell	powershell -File
.js, .jsx	JavaScript	node
.ts	TypeScript	node (via ts-node or tsx)

See examples/skills/ for complete reference packages.

Bundled Skills — Zero Configuration Required

dcc-mcp-core ships core skills directly inside the wheel. They are available immediately after pip install dcc-mcp-core — no repository clone or DCC_MCP_SKILL_PATHS configuration needed.

Skill	Tools	Purpose
app-ui	snapshot, find, act, wait_for	Scoped application UI observation/action mock backend
dcc-diagnostics	screenshot, audit_log, tool_metrics, process_status	Observability & debugging for any DCC
media	probe, sequence_to_mp4, transcode, extract_frames, thumbnail	vx-managed FFmpeg media processing for render/playblast artifacts
workflow	run_chain	Multi-step action chaining with context propagation

from dcc_mcp_core import get_bundled_skills_dir, get_bundled_skill_paths

print(get_bundled_skills_dir())
# /path/to/site-packages/dcc_mcp_core/skills

paths = get_bundled_skill_paths()                       # default ON
paths = get_bundled_skill_paths(include_bundled=False)  # opt-out

DCC adapters (e.g. dcc-mcp-maya) include the bundled skills by default. To opt out: start_server(include_bundled=False). The media skill uses vx ffmpeg / vx ffprobe internally so fresh machines do not need a manual FFmpeg install. If vx is missing, non-read-only media tools bootstrap vx with the official install script before retrying; the read-only probe tool reports vx_not_found instead of installing anything.

---

Solving MCP Context Explosion

The problem: Stock MCP returns all tools in tools/list, even those irrelevant to the current task or DCC instance. With 3 DCC instances × 50 skills × 5 scripts = 750 tools, the context window fills instantly.

Progressive discovery — dcc-mcp-core shrinks this to what the agent actually needs:

1. Skill stubs — direct per-DCC tools/list returns discovery/lifecycle meta-tools plus one stub per unloaded skill (__skill__<name>). Agents call search_skills(query) → load_skill(name) to activate the real tools; gateway tools/list stays bounded to discover/describe/call wrappers and uses gateway://instances / gateway://diagnostics/* resources for management views.
2. Instance awareness — Each DCC registers its active documents, PID, display name, scope level.
3. Smart tool scoping — Tools filter by DCC type, trust scope (Repo < User < System < Admin), product whitelist, and policy.
4. Session isolation — An AI session is pinned to one DCC instance; it sees only that instance's tools.
5. Gateway election — When a newer DCC version launches, traffic automatically hands off to it.

Stock MCP:

tools/list response:
  100 Maya + 100 Houdini + 100 Blender + 250 shared = 550 tool definitions

With dcc-mcp-core (Skills-First):

tools/list response (Maya session, nothing loaded yet):
  small core surface + 22 skill stubs
→ agent loads only the 3 skills it needs → ~30 tools in context

---

Highlights

• Rust-powered performance — Zero-copy serialisation (rmp-serde), LZ4 shared memory, lock-free data structures.
• Zero third-party Python library deps — Core logic is compiled into the native extension; the companion dcc-mcp-server wheel supplies the gateway daemon binary.
• Skills-First MCP server — create_skill_server() gives a ready-to-use MCP 2025-03-26 Streamable HTTP endpoint with progressive discovery.
• Workflow primitive — WorkflowSpec / WorkflowExecutor: declarative multi-step workflows with retry, timeout, idempotency keys, approval gates, foreach / parallel / branch steps, SQLite-backed recovery.
• Scheduler — Cron + webhook (HMAC-SHA256) triggered workflows via sibling schedules.yaml (opt-in feature).
• Artefact hand-off — Content-addressed (SHA-256) FileRef + ArtefactStore for passing files between tools and workflow steps.
• Job lifecycle & notifications — Opt-in async tools/call, SSE channels (notifications/progress, $/dcc.jobUpdated, $/dcc.workflowUpdated), optional SQLite persistence surviving restarts.
• Resources & Prompts primitives — Live DCC state (scene://current, capture://current_window, audit://recent, artefact://sha256/<hex>) and reusable prompt templates from sibling YAML.
• Thread affinity — DeferredExecutor routes main-thread-only tools to the DCC's event loop safely; Tokio workers handle the rest.
• Gateway & multi-instance — Version-aware first-wins election, SSE multiplex across sessions, async dispatch + wait-for-terminal passthrough.
• Resilient IPC — DccLink framing over ipckit (Named Pipe / Unix Socket): IpcChannelAdapter, GracefulIpcChannelAdapter, SocketServerAdapter.
• Process management — Launch, monitor, auto-recover DCC processes.
• Sandbox security — Policy-based access control with audit logging; ToolAnnotations safety hints; ToolValidator schema validation.
• Screen capture — Full-screen or per-window (HWND PrintWindow) viewport capture for AI visual feedback.
• USD integration — Universal Scene Description read/write bridge.
• Structured telemetry — Tracing, recording, optional Prometheus /metrics exporter.
• 380+ public Python symbols via top-level re-exports; _core.pyi is generated after a stub-gen/dev build rather than hand-edited source.

---

Architecture Overview — 47 Workspace Packages

dcc-mcp-core is organised as a Rust workspace of 47 packages (46 functional packages + workspace-hack). Most library crates compile into the native Python extension (_core) via PyO3 / maturin, while operator-facing crates such as dcc-mcp-cli, dcc-mcp-server, and tunnel binaries also ship as release assets. The root Cargo.toml is the source of truth for membership. Selected crates:

Crate	Responsibility	Key Types
dcc-mcp-naming	SEP-986 naming validators	validate_tool_name, validate_action_id, TOOL_NAME_RE
dcc-mcp-models	Data models	ToolResult, SkillMetadata, ToolDeclaration
dcc-mcp-actions	Tool execution lifecycle	ToolRegistry, ToolDispatcher, ToolValidator, ToolPipeline, EventBus
dcc-mcp-app-ui	App UI observation/action contracts	UiSnapshot, UiActionRequest, UiWaitCondition, AppUiPolicy
dcc-mcp-skills	Skills discovery & loading	SkillScanner, SkillCatalog, SkillWatcher, dependency resolver
dcc-mcp-protocols	MCP protocol-facing models	ToolDefinition, ResourceDefinition, PromptDefinition, ToolAnnotations, BridgeKind
dcc-mcp-jsonrpc	MCP JSON-RPC wire types	JsonRpcRequest, JsonRpcResponse, notifications
dcc-mcp-job	Async job tracking	JobManager, persistence traits
dcc-mcp-skill-rest	Per-DCC REST skill API	SkillRestService, SkillRestConfig, /v1/* router
dcc-mcp-gateway-core	Pure gateway domain layer	CapabilityRecord, SearchQuery, SearchHit, ranking scorers, slug helpers
dcc-mcp-gateway	Multi-DCC gateway app/infra	registry probing, MCP search / describe, REST /v1/* facade
dcc-mcp-http-types	Pure HTTP wire/config/value types	HttpError, JobConfig, InstanceConfig, PromptSpec, ProducerContent, SessionLogMessage
dcc-mcp-http-server	Reusable HTTP runtime support	core tool builders, executor, sessions, in-flight requests, notifications, workspace roots
dcc-mcp-catalog	Public adapter catalog	catalog search / describe CLI and MCP tools
dcc-mcp-transport	IPC communication	DccLinkFrame, IpcChannelAdapter, GracefulIpcChannelAdapter, SocketServerAdapter, FileRegistry
dcc-mcp-process	Process management	PyDccLauncher, PyProcessMonitor, PyProcessWatcher, PyCrashRecoveryPolicy, HostDispatcher
dcc-mcp-sandbox	Security	SandboxPolicy, SandboxContext, InputValidator, AuditLog
dcc-mcp-shm	Shared memory	PySharedBuffer, PySharedSceneBuffer, LZ4 compression
dcc-mcp-capture	Screen capture	Capturer, WindowFinder, HWND / DXGI / X11 / Mock backends
dcc-mcp-telemetry	Observability	TelemetryConfig, ToolRecorder, ToolMetrics, optional Prometheus
dcc-mcp-usd	USD integration	UsdStage, UsdPrim, scene_info_json_to_stage
dcc-mcp-http	MCP Streamable HTTP facade	McpHttpServer, McpHttpConfig, McpServerHandle, PyO3 bindings, compatibility re-exports
dcc-mcp-cli	Client control-plane CLI	dcc-mcp-cli list/search/load-skill/reload-skills/describe/call/wait-ready/stop-instance/install
dcc-mcp-server	Binary entry point	dcc-mcp-server CLI, gateway runner
dcc-mcp-sidecar	Sidecar runtime	SidecarArgs, sidecar MCP dispatch listener, gateway daemon guardian helpers
dcc-mcp-workflow	Workflow engine (opt-in)	WorkflowSpec, WorkflowExecutor, WorkflowHost, StepPolicy, RetryPolicy
dcc-mcp-scheduler	Cron + webhook scheduler (opt-in)	ScheduleSpec, TriggerSpec, SchedulerService, HMAC verification
dcc-mcp-artefact	Content-addressed artefact store	FileRef, FilesystemArtefactStore, InMemoryArtefactStore
dcc-mcp-logging	Rolling file logging	FileLoggingConfig, log retention helpers
dcc-mcp-paths	Platform path helpers	cache/config/data directory helpers
dcc-mcp-pybridge	PyO3 bridge helpers	repr/to-dict macros, JSON/YAML bridge
dcc-mcp-host	Host execution bridge	adapter-facing execution contracts
dcc-mcp-tunnel-*	Remote MCP relay	tunnel protocol, relay, and local agent

---

Selected APIs

Transport Layer — Inter-Process Communication

from dcc_mcp_core import DccLinkFrame, IpcChannelAdapter, SocketServerAdapter

# Server: create channel and wait for client
server = IpcChannelAdapter.create("dcc-mcp-maya")
server.wait_for_client()

# Client: connect to server
client = IpcChannelAdapter.connect("dcc-mcp-maya")
client.send_frame(DccLinkFrame(msg_type="Call", seq=1, body=b'{"method":"ping"}'))
reply = client.recv_frame()      # DccLinkFrame(msg_type, seq, body)

# Multi-client socket server (for bridge-mode DCCs)
sock_server = SocketServerAdapter("/tmp/dcc-mcp.sock",
                                  max_connections=10,
                                  connection_timeout_secs=30)

Process Management — DCC Lifecycle Control

from dcc_mcp_core import (
    PyDccLauncher, PyProcessMonitor, PyProcessWatcher, PyCrashRecoveryPolicy,
)

launcher = PyDccLauncher(dcc_type="maya", version="2025")
process = launcher.launch(
    script_path="/path/to/startup.py",
    working_dir="/project",
    env_vars={"MAYA_RENDER_THREADS": "4"},
)

monitor = PyProcessMonitor()
monitor.track(process)
stats = monitor.stats(process)     # CPU, memory, uptime

watcher = PyProcessWatcher(
    recovery_policy=PyCrashRecoveryPolicy(max_restarts=3, cooldown_sec=10),
)
watcher.watch(process)

Sandbox Security — Policy-Based Access Control

from dcc_mcp_core import SandboxContext, SandboxPolicy, InputValidator

policy = SandboxPolicy()
ctx = SandboxContext(policy)
validator = InputValidator(ctx)

allowed, reason = validator.validate("delete_all_files")
if not allowed:
    print(f"Blocked by policy: {reason}")

# Audit trail
for entry in ctx.audit_log.entries():
    print(f"{entry.action} -> {entry.outcome}")

Workflow & Artefact Hand-off (v0.14+)

from dcc_mcp_core import (
    WorkflowSpec, BackoffKind,
    artefact_put_bytes, artefact_get_bytes,
)

spec = WorkflowSpec.from_yaml_str(yaml_text)
spec.validate()                    # static idempotency_key + template check
print(spec.steps[0].policy.retry.next_delay_ms(2))

ref = artefact_put_bytes(b"hello", mime="text/plain")
print(ref.uri)                     # "artefact://sha256/<hex>"
assert artefact_get_bytes(ref.uri) == b"hello"

See AGENTS.md for the full feature matrix and decision tree.

---

Development Setup

git clone https://github.com/dcc-mcp/dcc-mcp-core.git
cd dcc-mcp-core

# Recommended: use vx (universal dev tool manager) — https://github.com/loonghao/vx
vx just dev            # build + install dev wheel (uses canonical feature set)
vx just test           # run Python tests
vx just test-rust      # run Rust unit/integration tests
vx just lint           # full lint check (Rust + Python)
vx just preflight      # pre-commit checks (cargo check + clippy + fmt + test-rust)
vx just ci             # full local CI pipeline

Without vx

python -m venv venv
source venv/bin/activate   # Windows: venv\Scripts\activate
pip install maturin pytest pytest-cov ruff mypy

# The canonical feature list lives in the root justfile — see `just print-dev-features`.
maturin develop --features "$(just print-dev-features)"
pytest tests/ -v
ruff check python/ tests/ examples/
cargo clippy --workspace -- -D warnings

The feature list is the single source of truth in justfile (OPT_FEATURES, DEV_FEATURES, WHEEL_FEATURES, WHEEL_FEATURES_PY37). CI, local dev, and release wheels all read from the same place.

---

Release Process

This project uses Release Please to automate versioning and releases:

1. Develop: Create a branch from main and commit using Conventional Commits.
2. Merge: Open a PR and merge to main.
3. Release PR: Release Please automatically creates / updates a release PR that bumps the version and updates CHANGELOG.md.
4. Publish: When the release PR merges, a GitHub Release is created with dcc-mcp-cli and dcc-mcp-server binaries, and separate PyPI jobs publish dcc-mcp-core, dcc-mcp-server, and dcc-mcp-core-semantic wheels through Trusted Publishing.

Commit Message Format

Prefix	Description	Version Bump
feat:	New feature	Minor (0.x.0)
fix:	Bug fix	Patch (0.0.x)
feat!: or BREAKING CHANGE:	Breaking change	Major (x.0.0)
docs:	Documentation only	No release
chore:	Maintenance	No release
ci:	CI/CD changes	No release
refactor:	Code refactoring	No release
test:	Adding tests	No release
build:	Build system / dependency changes	No release

git commit -m "feat: add batch skill execution support"
git commit -m "fix: resolve middleware chain ordering issue"
git commit -m "feat!: redesign skill registry API"
git commit -m "feat(skills): add PowerShell script support"
git commit -m "docs: update API reference"

---

Contributing

Contributions are welcome — please open a Pull Request.

1. Fork the repository and clone your fork.
2. Create a feature branch: git checkout -b feat/my-feature.
3. Make your changes following the coding standards below.
4. Run tests and linting:

   vx just lint        # check code style
   vx just test        # run tests
   vx just preflight   # run all pre-commit checks
   

5. Commit using Conventional Commits.
6. Push and open a Pull Request against main.

Coding Standards

• Style: Rust via cargo fmt, Python via ruff format (line length 120, double quotes).
• Type hints: All public Python APIs must have type annotations; Rust uses thiserror for errors and tracing for logging.
• Docstrings: Google-style docstrings for all public modules, classes, and functions.
• Testing: New features must include tests; maintain or improve coverage.
• Imports (Python): from __future__ import annotations first, then stdlib → third-party → local with section comments.

---

License

MIT — see the LICENSE file.

---

AI Agent Resources

If you're an AI coding agent, also read:

• AGENTS.md — Navigation map for AI agents (entry point, decision tables, top traps).
• docs/guide/agents-reference.md — Detailed agent rules, traps, code style, and project-specific architecture constraints.
• .agents/skills/dcc-mcp-core/SKILL.md — Complete API skill definition.
• python/dcc_mcp_core/__init__.py — Full public API surface (380+ symbols).
• python/dcc_mcp_core/_core.pyi — Ground-truth type stubs (parameter names, types, signatures).
• llms.txt — Concise API reference optimised for LLMs.
• llms-full.txt — Complete API reference optimised for LLMs.
• CONTRIBUTING.md — Development workflow and coding standards.