Maya MCP Resources

Issue #187 wires dcc-mcp-maya into the Rust ResourceRegistry shipped by dcc-mcp-core 0.15.0. Out of the box, MCP clients now see:

• scene://current — JSON snapshot of the live Maya scene (pid, dcc, scene, selection, frame, frame_range, up_axis, units, version, ...). Refreshed by Maya scriptJob events whenever the scene changes; throttled to one publish per 500 ms to absorb DagObjectCreated storms during bulk imports.
• maya-cmds://help/<command> — cmds.help(command, language="python") output for any Maya command name.
• maya-cmds://flags/<command> — flag enumeration via cmds.help(command, flags=True).
• maya-api://signatures/<class> — public-method index for maya.api.OpenMaya / OpenMayaAnim / OpenMayaUI classes (e.g. maya-api://signatures/MFnMesh).
• maya-project://current — active workspace root + fileRule table for the running Maya session.

Quick check

Once you have dcc_mcp_maya.start_server() running, point an MCP client (Claude Desktop, Cursor, etc.) at the printed URL and watch the resource surface light up:

// resources/list
{
  "resources": [
    { "uri": "scene://current", "name": "Current Scene", "mimeType": "application/json" },
    { "uri": "capture://current_window", ... },
    { "uri": "audit://recent", ... },
    { "uri": "maya-cmds://", "name": "Python-provided resource (maya-cmds)" },
    { "uri": "maya-api://", "name": "Python-provided resource (maya-api)" },
    { "uri": "maya-project://", "name": "Python-provided resource (maya-project)" }
  ]
}

// resources/read scene://current  (after a scene is open)
{
  "contents": [{
    "uri": "scene://current",
    "mimeType": "application/json",
    "text": "{\"available\":true,\"dcc\":\"maya\",\"scene\":\"/projects/foo/scenes/sh_010.ma\",...}"
  }]
}

// resources/read maya-cmds://help/polySphere
{
  "contents": [{
    "uri": "maya-cmds://help/polySphere",
    "mimeType": "text/plain",
    "text": "polySphere is undoable, queryable, and editable.\n\nFlags:\n -axis  -ax ..."
  }]
}

Throttling: how scene://current stays cheap

Maya's DagObjectCreated event fires once per node during scene imports. Importing a 1000-node character into a clean scene therefore fires 1000 events back-to-back; without throttling the server would push 1000 notifications/resources/updated SSE frames per import.

The Maya adapter collapses these bursts to at most one publish per 500 ms using a lead-edge + trail-edge timer:

Scenario	Publishes (typical)
Single edit (e.g. node rename)	1 (lead-edge)
50-node import (50 ms)	1 (trail-edge after 500 ms)
1000-node import (2 s)	~5 (one per 500 ms window)
Continuous edit storm	~2 per second (steady-state)

Tune the throttle window (0.5 s default) by passing throttle_secs=... when constructing MayaResourceBinder.

Configuration

Variable	Default	Effect
DCC_MCP_MAYA_RESOURCES	1	Set to 0 to disable Maya resource publishing entirely.

When disabled, scene://current stays at the core default {"status": "no_scene_published"} and the three maya-*:// schemes are not registered. Use this to let an embedding host drive scene://current itself.

Python API

from dcc_mcp_maya import (
    MayaResourceBinder,    # SOLID composition root
    install_resources,     # one-shot helper
    SCHEME_MAYA_CMDS,
    SCHEME_MAYA_API,
    SCHEME_MAYA_PROJECT,
    DEFAULT_SCENE_EVENTS,  # tuple of scriptJob event names we hook
    DEFAULT_SCENE_THROTTLE_SECS,
)

install_resources(server, *, snapshot_provider=None, install_scene_events=True, throttle_secs=0.5)

Called automatically by MayaMcpServer.register_builtin_actions() right after register_project_tools. The default snapshot_provider is the same MayaContextSnapshotProvider.collect callable used by the /v1/context REST endpoint, so scene://current and /v1/context report identical state.

MayaResourceBinder

The composition root. Every call into server._server.resources() lives in this class so future schema migrations are a single-file edit. Skill scripts and plugin code must not reach into the raw ResourceHandle; use the binder via MayaMcpServer._resources if you need to publish ad-hoc updates.

# Force a fresh publish (e.g. after a scripted edit your scriptJob
# events don't catch).
server._resources.publish_scene()                      # uses provider
server._resources.publish_scene({"explicit": "value"}) # bypass provider

Authoring custom producers

Drop-in for skills that want to expose a custom URI scheme. Create the producer in your skill module and register it from a startup hook:

def my_camera_producer(uri: str) -> dict:
    """maya-camera://<camera_name> → JSON description of the camera."""
    name = uri.removeprefix("maya-camera://")
    import maya.cmds as cmds
    return {
        "mimeType": "application/json",
        "text": json.dumps({
            "focal_length": cmds.getAttr(f"{name}.focalLength"),
            "translate":    cmds.getAttr(f"{name}.translate")[0],
        }),
    }

# Register once, after MayaMcpServer.register_builtin_actions:
server._resources.handle.register_producer(
    "maya-camera://", my_camera_producer
)

Prompts (next-tools, examples) — current status

Core 0.15.0 advertises prompts: {listChanged: true} and prompts/list returns an empty array. PR #373 implemented prompt derivation from SKILL.md examples and workflows, but the wheel shipped with 0.15.0 still returns [] for adapters that ship those fields. When the consumption path is live (0.15.1+), bundled Maya skills will surface their examples automatically — no Maya-side code change required.

See also

• AGENTS.md — overview of the SOLID binder pattern (ReadinessBinder, ProjectToolsIntegration, MayaResourceBinder).
• docs/guide/scene.md — the existing scene-info tool surface, which now mirrors scene://current.