autocad-mcp

MCP server for AutoCAD LT automation and headless DXF generation.

Two backends, one API:

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.

• 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.

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

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.

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": "auto" }
    }
  }
}

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).

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 && .venv\\Scripts\\python.exe -m autocad_mcp"],
      "env": { "AUTOCAD_MCP_BACKEND": "auto" }
    }
  }
}

From your MCP client, call:

system(operation="status")

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

Create: create_line, create_circle, create_polyline, create_rectangle, create_arc, create_ellipse, create_mtext, create_hatch

Read: list, count, get

Modify: copy, move, rotate, scale, mirror, offset*, array, fillet*, chamfer*, erase

* offset, fillet, chamfer are File IPC only (not supported in ezdxf headless backend).

list, create, set_current, set_properties, freeze, thaw, lock, unlock

create_text, create_dimension_linear, create_dimension_aligned, create_dimension_angular, create_dimension_radius, create_leader

setup_layers, insert_symbol, list_symbols, draw_process_line, connect_equipment, add_flow_arrow, add_equipment_tag, add_line_number, insert_valve, insert_instrument, insert_pump, insert_tank

P&ID symbol insertion requires the CAD Tools Online (CTO) P&ID Symbol Library installed at C:\PIDv4-CTO\. The ezdxf backend has built-in CTO library support. For the File IPC backend, some P&ID operations require additional LISP helpers — see the P&ID section in the wiki for setup details.

Screenshots use PrintWindow (Win32) for the File IPC backend — works even when AutoCAD is minimized or in the background. The ezdxf backend renders via matplotlib.

status, health, get_backend, runtime, init, execute_lisp

execute_lisp runs arbitrary AutoLISP code (File IPC only). Pass data: {code: "(+ 1 2)"}. This turns the server into an extensible automation platform — any valid AutoLISP expression can be executed.

MCP Client (Claude)
    │  stdio (JSON-RPC)
    ▼
Python MCP Server (autocad_mcp)
    │
    ├── File IPC Backend ──► C:/temp/*.json ──► mcp_dispatch.lsp (AutoCAD LT)
    │   PostMessageW(WM_CHAR) to MDIClient — no focus steal
    │
    └── ezdxf Backend ──► in-memory DXF (headless, no AutoCAD needed)

The File IPC backend sends keystrokes to AutoCAD's MDIClient window via PostMessageW(WM_CHAR), triggering the (c:mcp-dispatch) AutoLISP command. This approach does not steal window focus — you can continue working in other applications while automation runs.

Note: If you change AUTOCAD_MCP_IPC_DIR, you must also update the *mcp-ipc-dir* variable in mcp_dispatch.lsp to match.

uv sync
uv run pytest tests/ -v

AutoLISP was added to AutoCAD LT in the 2024 release (Windows only). AutoCAD LT for Mac does not support AutoLISP.

The mcp_dispatch.lsp dispatcher is fully compatible with LT 2024+.

• execute_lisp — Run arbitrary AutoLISP code via temp file pattern. Turns the server from a fixed command set into an extensible automation platform.
• Undo / Redo — Single-step undo and redo via drawing tool.
• Drawing open — Open existing .dwg files programmatically (FILEDIA suppressed).
• Drawing create — Now resets current drawing (erase all + purge) instead of _.NEW, preserving the LISP dispatcher namespace.
• Drawing save with path — save with a path parameter uses SAVEAS; without path uses QSAVE.
• get_variables fix — Respects the names parameter; returns requested variables with proper type handling.
• Polyline/leader fix — Point arrays properly encoded via semicolon-delimited format.
• ESC prefix — Sends 2x ESC before each dispatch to cancel stale pending commands from prior timeouts.
• UTF-8/cp1252 fallback — Handles non-ASCII characters in LISP result files (AutoCAD writes Windows-1252).
• Configurable IPC timeout — AUTOCAD_MCP_IPC_TIMEOUT env var (1–300 seconds, default 10).
• Thread-safe backend init — asyncio.Lock prevents parallel initialization races.

MIT