autodesk-inventor-mcp

An MCP server for Autodesk Inventor. It lets an AI client — Claude, Cursor, or anything else that speaks MCP — model parts, build assemblies, and inspect what it just made.

Autodesk ships official MCP servers for Fusion, Revit and Product Help. Inventor has none, and none is announced. This fills that gap.

Status: alpha. Developed and tested against Inventor 2027 on Windows 11.

Why it works differently from the Fusion server

Fusion's MCP server runs inside Fusion, because Fusion has no out-of-process API — an add-in is the only way in. Inventor exposes a full COM automation interface, so this server is an ordinary external Python process:

• nothing to install into Inventor, and no add-in to rebuild per version

• a crash in the server does not take Inventor with it

• normal Python tooling and debugging

Related MCP server: solidworks-mcp

Things that turned out not to be true

Several widely repeated claims about Inventor automation did not survive measurement, and each one changed the design. All of them have a test that would fail if they stopped holding — details in docs/design.md §2.

1. Out-of-process COM does produce real solids (IsSolid == True, and a cylinder with 3 faces). The folklore that only in-process execution — an add-in or an iLogic rule — yields solids does not hold on 2027. If you got surfaces, look at how the profile was created, not at the process boundary.

2. iLogicAutomation.AddRule executes the rule as it adds it. Code that calls AddRule and then RunRule builds everything twice, and a trailing boolean usually hides the evidence.

3. A gen_py cache does not break .ComponentDefinition — the usual telling of the late-binding rule. What it actually does is hand back typed wrappers for child objects that expose only their declared interface, so a STEP translator arrives with no HasSaveCopyAsOptions, a feature with no .Operation, and an occurrence definition with no .WorkPlanes.

4. Inventor's object names are localised. On a zh-CN install the origin planes are 'XY 平面' and the structured BOM view is '结构化'. Any code that looks up "XY Plane" or "Structured" is en-US only. This server addresses them by index behind a language-independent shorthand.

5. Patterned instances are not new bodies. A circular pattern adds lumps to the seed's body; the body count does not move.

Install

Requires Windows and a licensed Inventor installation.

git clone https://github.com/xtylerai2026-oss/autodesk-inventor-mcp
cd autodesk-inventor-mcp
uv venv
uv pip install -e .

Claude Desktop / Claude Code

{
  "mcpServers": {
    "inventor": {
      "command": "path/to/autodesk-inventor-mcp/.venv/Scripts/inventor-mcp.exe"
    }
  }
}

HTTP transport

inventor-mcp --http --port 27183

Then point the client at http://127.0.0.1:27183/mcp. Running over HTTP keeps the Inventor connection warm across client restarts and can be poked with curl.

Usage

Start Inventor (or let the server start it), then just ask:

Make a 60 mm diameter, 20 mm tall boss with a 12 mm bore through it, and tell me the mass in aluminium.

The interesting part is not that it builds — it is that it checks. describe_model returns is_solid, face counts, volumes, and per-feature health, so a client can notice it accidentally produced a surface, or that a fillet failed, and fix it without being told.

Tools

24 tools in six groups. Full signatures in docs/design.md §5.

Read-only tools carry readOnlyHint, so clients can auto-approve inspection calls. That matters more than it sounds: the build-inspect-adjust loop only works if inspecting is free.

Units

Every length is millimetres and every angle is degrees, at every boundary. Inventor's own API works in centimetres and radians; this server converts at the edge so you never meet a silent 10× error.

Scope

Supported: part documents (.ipt) and assembly documents (.iam).

Assembly constraints work against named entities — work planes, axes, points, iMates. Constraints that require picking a particular face or edge are out of scope on purpose: Inventor has no stable name for a face and topological ids move on rebuild. Use run_python_com when you genuinely need one.

Not supported: drawings (.idw), sheet metal, CAM.

Development

uv pip install -e ".[dev]"
pytest                # 24 unit tests, no Inventor needed
pytest -m inventor    # 32 integration tests, drives a real Inventor

Current state on Inventor 2027 (build 310192060): 24 unit + 32 integration tests passing, 0 Inventor processes left behind.

Integration tests attach to a running Inventor if there is one and launch one otherwise — and call Quit() on teardown only if they launched it. Please keep it that way. Automation that forgets is how you end up with a pile of headless Inventor processes holding gigabytes; this project started by cleaning up nine of them.

Licence

MIT