AutoCAD AI Agent: Connect Claude to a Free CAD App with MCP

Short answer: AutoCAD doesn't come with an AI agent you can plug into Claude. CADCraft, a free open-source CAD program with AutoCAD-style commands, does: it ships an MCP server (cadcraft-cli mcp). Add it to Claude Code with one command, ask for a drawing in plain English, and the agent types the commands, checks the result and saves DXF, DWG or PDF.

claude mcp add cadcraft -- cadcraft-cli mcp

The setup takes a minute. Most of this page is about the part that decides whether you can trust the result: making the agent check what it drew, with two real mistakes from a real session.

cadcraft.org is an independent guide, not the official site and not affiliated with Autodesk. CADCraft is the ArtCraft team's open-source CAD program (getartcraft.com/apps/cadcraft). Everything below was run with cadcraft-cli 0.13.0.

What the agent can do

MCP (Model Context Protocol) is the standard way for AI clients like Claude Code and Claude Desktop to call outside tools. CADCraft's server gives the model 12 tools:

execute also reaches analysis commands such as shapes, which reports the area, perimeter and centroid of closed shapes, and loops, which finds closed outlines made of loose lines and arcs.

CADCraft doesn't include a language model. It's the hands and eyes; the model is whatever your MCP client uses.

Set it up

1. Install CADCraft. The download page has the installers. The Windows and Linux packages include cadcraft-cli; on macOS it's a separate cadcraft-cli-<ver>-macos-universal.zip on the release page. Check it's on your PATH:

cadcraft-cli --version

2. Add it to your client. For Claude Code:

claude mcp add cadcraft -- cadcraft-cli mcp

For Claude Desktop and other clients configured with JSON, add this to the client's MCP config and restart the client:

{ "mcpServers": { "cadcraft": { "command": "cadcraft-cli", "args": ["mcp"] } } }

3. Choose headless or bridged.

• Headless (the config above) runs a drawing session in memory with no window. It's fast and suits batch jobs: "make a DXF of this plate in six sizes".
• Bridged drives the desktop app so you can watch it draw and take over with the mouse. Start CADCraft with --control 7979, and point the client at it:

{
  "mcpServers": {
    "cadcraft": {
      "command": "cadcraft-cli",
      "args": ["mcp", "--connect", "127.0.0.1:7979", "--launch"]
    }
  }
}

MCP clients usually start their servers before you open the app. --launch (macOS) opens CADCraft with that port when the first tool call finds nothing; --lazy just waits for you to open it. With neither flag, the bridge fails to start when the app isn't running, rather than quietly editing a separate drawing.

A real session: a flange in four steps

We asked for this, in plain English:

New metric drawing. A flange: outer diameter 150, bore 80. Six 12 mm bolt holes equally spaced on a 115 pitch circle. Part outline on layer PART, holes on HOLES in red, the pitch circle on CENTER in green, dimensions on DIMS. Dimension both diameters and add the note "6X Ø12 ON Ø115 PCD". Then check it and save a DXF.

The tool calls were written by Claude (the model that writes this site's articles) and sent to cadcraft-cli mcp 0.13.0 over stdio. The plan: new_drawing {"metric": true}, a script with the circles and layers, one hole drawn at (57.5, 0), then execute with arraypolar to make the other five, then the dimensions and note. Here's the result, rendered by the render tool:

It looks right. Two things went wrong on the way, and neither showed in a picture.

Mistake 1: six holes in the picture, zero circles in the drawing

The first arraypolar call used the defaults:

{
  "command": "arraypolar",
  "params": { "handles": ["103"], "center": [0, 0], "count": 6 }
}

It replied {"associative": true, "created": 5, "handle": "10B"}. The render showed six holes. But query_entities {"type": "Circle", "layer": "HOLES"} returned 0. Everything on HOLES was one Block Reference. Like AutoCAD, CADCraft makes arrays associative by default: the six holes are one array object, not six circles.

That matters if the next step is "dimension each hole" or "count the holes for the BOM". The fix was to undo and pass "associative": false. The query then listed six circles, each Ø12 and exactly 57.5 from the centre: (57.5, 0), (28.75, 49.796), (−28.75, 49.796), (−57.5, 0), (−28.75, −49.796), (28.75, −49.796).

Mistake 2: a pick point that landed on the wrong object

The agent dimensioned the bore with dimdiameter -28.28,-28.28 …, a point on the Ø80 circle at 225°. CADCraft answered Object selected is not a circle or arc. The reason: the Ø150 diameter dimension it had just drawn runs from 45° to 225° straight through that point, so the pick found the dimension, not the circle.

Two lessons. The tool result didn't set isError, because the command ran and only complained at its prompt, so the agent has to read the output text, not just the status. And the script kept going: the prompt ate the next lines, so the note was never written. inspect_drawing caught it (Circle 9, Dimension 1, no Text). Picking at (−40, 0) instead, where nothing else crosses, fixed it.

The checks that proved it

After the fixes:

• inspect_drawing: Circle 9, Dimension 2, Text 1 on layers PART, CENTER, HOLES, DIMS.
• execute shapes {"layer": "PART"}: two circles, areas 17,671.46 and 5,026.55 mm², so the flange face is 12,644.91 mm² before the bolt holes.
• save {"path": "flange.dxf"}: a 20,819-byte DXF, 2018 format.

How to prompt a CAD agent

• Give every number. Sizes, positions, counts, units. "A flange for a 2-inch pipe" makes the model guess.
• Name the layers and colours. You'll want them when you edit the drawing later.
• Ask for the check in the prompt. "Then list the circles on HOLES with their centres and diameters" makes verification part of the job.
• Ask for JSON commands when objects are picked. execute with handles is more reliable than clicking at coordinates, which is what went wrong in mistake 2.
• Say "metric" at the start. new_drawing {"metric": true}. An imperial drawing reads 150 as 150 inches.
• Review before it goes to a fabricator. The agent draws what you said. Tolerances, threads and finishes aren't on the drawing unless you asked.

What an AI agent in CAD is good for (today)

Good: fully specified 2D parts (plates, flanges, gaskets, brackets), repeating a drawing in several sizes, cleaning up DXF files (layers, purging, renaming), reading a drawing and answering questions ("what's the area of every closed room outline on A-WALL?"), and batch exports.

Not yet: design decisions, anything that depends on engineering judgement, and 3D. CADCraft is 2D and pre-alpha; for prompt-to-3D see the parametric-script route in text to CAD.

FAQ

Related

• Text to CAD: what actually works today: the three routes, and a runnable Python MCP example
• CAD in Rust: how CADCraft is built, and why every action is a command
• AutoCAD commands cheat sheet: the commands an agent types