acad-mcp — let Claude drive AutoCAD

Português

An MCP server that lets Claude (and other MCP clients) draw, edit, read and check drawings in the AutoCAD running on your Windows PC — and process whole folders of DWGs without opening them.

• 61 tools + a guided prompt, every write is one undo step (Ctrl+Z).
• Fast on large drawings: reads run as LISP inside AutoCAD — 50,000 entities in ~15 s (vs ~22 min over COM).
• Batch: run a routine or a layer standard over a folder with AutoCAD's console engine (no window, in parallel). Originals are never modified — copies go to an output folder.
• Routines without AI: built-in LISP routines (find/replace, fill title blocks, export attributes, count blocks, layer standard from CSV, purge/audit, plot PDF) that a person can also type as MCP_... commands.
• Recreate drawings: import vector PDFs with real measurements, DXF/DWG, or trace scans/photos into lines; a coordinate grid on screenshots lets the model compare and fix.
• English and Portuguese (ACAD_MCP_LANG=pt).

AutoCAD is a registered trademark of Autodesk, Inc. This project is not affiliated with or endorsed by Autodesk.

Requirements

• Windows and the full AutoCAD (uses COM/ActiveX). AutoCAD LT is not supported (no COM, no console). Tested on AutoCAD 2027; earlier versions (2021+) are likely to work but are not verified.
• uv (it installs Python 3.13 for you).
• Linux/macOS: not possible — AutoCAD's automation only exists on Windows.

Install

Claude Desktop — extension (easiest)

Download acad-mcp-<version>.mcpb from the Releases page and open it with Claude Desktop (Settings → Extensions). Options: language, read-only, LISP on/off, auto-restore window.

Claude Desktop — config file

{
  "mcpServers": {
    "acad": { "command": "uvx", "args": ["acad-mcp"], "env": { "ACAD_MCP_LANG": "en" } }
  }
}

Edit the config with Claude fully closed (tray icon → Quit): Claude rewrites the file from memory when it quits, which would drop your change.

One-click install from this folder (Windows)

Double-click INSTALAR.bat: it checks AutoCAD, asks the language, closes Claude (after asking), installs uv if missing, installs Python and the dependencies, configures Claude (with a backup), runs a self-test and reopens Claude. A .venv copied from another PC is detected and rebuilt.

Claude Code

claude mcp add --scope user acad -- uvx acad-mcp

Other MCP clients

Any client that runs local stdio servers: command uvx, args ["acad-mcp"]. For HTTP: acad-mcp --http (listens on 127.0.0.1:8765/mcp only).

Use

Open AutoCAD and keep its window not minimized (it may stay behind other windows). Then ask, e.g.:

• "Create layers WALL (red, 0.35) and AXIS (green, CENTER) and draw a 4 × 3 m room with axes and dimensions."
• "Count the blocks and export their attributes to a CSV on my Desktop."
• "Check this drawing against the example standard and fix what you can."
• "In C:\Projects\Sheets, replace 'REV A' with 'REV B' in every drawing." (batch, originals untouched)
• "Recreate the attached part directly in AutoCAD with dimensions, then show me."

Tools

Prompt: recreate_drawing — measurements first, ask for what is missing, draw, compare, fix.

Configuration

How it works (and what was measured)

• One COM thread talks to AutoCAD; a COM message filter retries calls while AutoCAD is busy, so a tool is never re-run (re-running duplicated saves during development).
• Commands/LISP go through SendCommand with a watchdog: if a command waits for input, ESC is sent to the drawing area (ESC to the main window does not cancel). The command line rejects expressions over ~1–2 k characters, so long LISP is written to a temp file and read+evaluated (reading text does not trigger SECURELOAD, unlike (load)).
• With the window minimized, SendCommand gets queued and AutoCAD freezes when restored, so commands, LISP and screenshots refuse to run minimized (unless auto-restore is on). Direct drawing/editing works minimized.
• COM selection sets leave internal "OLEAPPLICATION" undo records; undo skips them.
• Batch console engine (accoreconsole.exe): pure AutoLISP and vlax-curve-* work, vla-* does not; plotting to PDF and saving work. Measured: 3 files in ~1.5 s with 3 workers. Use engine="gui" for vla-* routines and JSON standards.
• PDF import: -PDFIMPORT runs without a dialog. PDFs plotted by AutoCAD came back at real size; PDFs without CAD scale come in inches (1 pt = 1/72") — rescale and check one known measurement.
• trace_image is a draft: straight strokes within ~1 % on clean drawings in tests; curves and text are not traced.

Safety

• Never writes over an existing file without overwrite=true; closing with unsaved changes needs discard_changes=true; batch only touches copies.
• run_command blocks SHELL, START, NETLOAD, APPLOAD, SCRIPT, QUIT and similar; file dialogs are off.
• run_lisp blocks startapp, file deletion/renaming, registry writes, etc. It is not a sandbox — LISP can do a lot. Disable it with ACAD_MCP_ALLOW_LISP=0 or use read-only mode.
• HTTP mode listens on localhost only. Never expose it publicly without authentication: whoever reaches it controls your AutoCAD. See SECURITY.md.

ChatGPT

ChatGPT only talks to remote MCP servers. See docs/chatgpt.md (OpenAI Secure MCP Tunnel; not fully verified yet).

Development

uv sync
uv run pytest -m "not live"     # no AutoCAD needed
uv run pytest                   # also the live tests: AutoCAD open, window not minimized
uv build                        # wheel + sdist
uv run python scripts/build_mcpb.py   # Claude Desktop extension (needs Node.js)

The live tests create their own drawings and close them without saving; they never touch yours.

License

MIT — see LICENSE.