AutoCAD MCP Server

PuranOS role and current scope

This is an active drawing-automation integration used alongside the PuranOS engineering workflow. AutoCAD LT and headless DXF are distinct backends with the platform requirements below. The current guarded revision helpers operate on an explicitly identified working drawing; engineering basis, canonical equipment records and release decisions live in the wider workflow.

Sizing-to-balance, proposals and BEPs produce the engineering basis. PuranOS Studio presents retained review publications. Neither a successful CAD command nor a screenshot approves a design. This repository is maintained separately from the six-server public calculation mirror.

Built by Puran Water · Discuss engineering or a drawing workflow.

MCP server for AutoCAD LT automation and headless DXF generation.

Two backends, one API:

Backend	Runtime	Requires AutoCAD?	Screenshot
File IPC	Windows Python	Yes — AutoCAD LT 2024+ (Windows)	Win32 PrintWindow
ezdxf	Any platform	No (headless)	matplotlib render

The server exposes 8 consolidated tools (drawing, entity, layer, block, annotation, pid, view, system) over the MCP stdio transport. An MCP client (Claude Desktop, Claude Code, etc.) connects and drives AutoCAD through natural-language requests.

Prerequisites (File IPC backend)

• Windows 10/11 (the File IPC backend uses Win32 APIs for focus-free window messaging)
• AutoCAD LT 2024 or newer — AutoLISP support was added in LT 2024 for Windows. AutoCAD LT for Mac exists but does not support AutoLISP.
• Python 3.10+ (Windows native — not WSL Python)
• uv package manager (install guide)

The ezdxf headless backend works on any platform (Linux, macOS, WSL) for offline DXF generation without AutoCAD installed.

Quick Start

1. Clone and install

git clone https://github.com/puran-water/autocad-mcp.git
cd autocad-mcp
uv sync

2. Load the LISP dispatcher in AutoCAD LT

Open AutoCAD LT and load mcp_dispatch.lsp using APPLOAD:

1. Type APPLOAD in the AutoCAD command line
2. Browse to <repo>/lisp-code/mcp_dispatch.lsp
3. Click Load
4. You should see: === MCP Dispatch v3.1 loaded === and Ready for commands via (c:mcp-dispatch)

Tip: Add the file to your AutoCAD Startup Suite (in the APPLOAD dialog) so it loads automatically with every drawing.

3. Configure your MCP client

Add to your MCP client configuration (e.g. Claude Desktop claude_desktop_config.json):

{
  "mcpServers": {
    "autocad-mcp": {
      "command": "C:\\path\\to\\autocad-mcp\\.venv\\Scripts\\python.exe",
      "args": ["-m", "autocad_mcp"],
      "env": { "AUTOCAD_MCP_BACKEND": "file_ipc" }
    }
  }
}

Key points:

• The command must point to the Windows Python inside the project venv (not WSL python).
• AUTOCAD_MCP_BACKEND can be auto (default — tries File IPC, falls back to ezdxf), file_ipc (requires AutoCAD), or ezdxf (headless only).

Running from WSL

If your MCP client runs in WSL (e.g. Claude Code), launch the server through cmd.exe so it runs as a native Windows process:

{
  "mcpServers": {
    "autocad-mcp": {
      "type": "stdio",
      "command": "cmd.exe",
      "args": ["/d", "/s", "/c", "cd /d C:\\path\\to\\autocad-mcp && set AUTOCAD_MCP_BACKEND=file_ipc&& .venv\\Scripts\\python.exe -m autocad_mcp"]
    }
  }
}

4. Verify

From your MCP client, call:

system(operation="status")

You should see backend: "file_ipc" if AutoCAD is running, or backend: "ezdxf" for headless mode.

For native DWG work, require file_ipc; the examples above disable headless fallback. Verify DWGNAME, DWGPREFIX, CTAB and DBMOD with drawing.get_variables, then inspect a screenshot before editing. status alone does not identify the active DWG. Use a Windows-local working copy if Windows cannot access a WSL UNC path, and copy saved deliverables back explicitly. Never use drawing.create to make a working copy: it erases and purges the active drawing.

Journaled native revisions

system(operation="revision", data={"action": "read", "drawing": "C:/work/copy.dwg", "handles": ["ABCD"]}) reads native entities. The revision adapter supports bounded exports, layout frames, guarded edits, plotting and AutoCAD 2010 saves. Each mutation batch has 1–7 operations, a unique journal path, expected document identity and old entity values. Receipts retain before/after state and created handles. Read the operation reference and recovery procedure before use.

Revision clouds can follow an orthogonal route instead of enclosing unrelated labels:

{
  "action": "batch",
  "drawing": "C:/work/copy.dwg",
  "id": "route-cloud-01",
  "journal": "C:/work/route-cloud-01.json",
  "operations": [{
    "kind": "cloud", "item": "approved-change-42",
    "space": "Model", "layer": "REV-01",
    "points": [[0,0], [8,0], [8,2], [2,2], [2,8], [0,8]],
    "arc": 0.4, "text_height": 0.3, "revision": "01",
    "marker_position": [10,3]
  }]
}

Create the revision layer first. Pass this object to system with operation="revision". For the Windows CLI, save the object as request.json (the extra action is ignored):

python -m autocad_mcp.revision batch request.json --output receipt.json

An existing MCP session can use the updated helper through execute_lisp without acquiring a new tool schema: replace action with operation in the request, then compile on WSL and submit the resulting expression as data.code:

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