CAD MCP Server

Give your AI assistant the ability to inspect, measure, and compare 3D CAD models. Drop in a STEP file, ask engineering questions, get measured answers. Runs entirely on your machine — no cloud, no CAD license, no setup.

Quick Start

Terminal

npx -y cad-mcp-server

Add to your MCP client:

config.json

{
  "mcpServers": {
    "cad": {
      "command": "npx",
      "args": ["-y", "cad-mcp-server"]
    }
  }
}

Point your AI at any STEP file and ask questions like:

"Review this part before manufacturing. Check wall thickness, draft angles, and hole sizes. Flag anything that violates standard DFM rules."

Why Engineers Use It

Zero setup. One command. No CAD software, licenses, Docker, or cloud API.
Runs locally. Your STEP files never leave your machine.
Deterministic answers. Backed by the Open CASCADE kernel, not LLM guessing.
Read-only. Inspects geometry without modifying anything.

What It Can Do

Tool	Example question
`inspect_step`	"What are the overall dimensions and volume?"
`find_faces`	"Find all cylindrical faces. Which ones are holes vs bosses?"
`find_edges`	"What's the smallest fillet radius on this part?"
`measure_geometry`	"Check wall thickness around every hole. Flag anything below 2mm."
`diff_step`	"What changed between revision A and revision B?"

The AI assistant interprets the measurements. You get engineering answers, not raw numbers.

Example Prompts

"Review this part for injection molding: check draft angles with +Z pull, measure minimum wall thickness, identify undercuts."
"Prepare a first-pass CNC plan: likely setups, drilling directions, features that drive cost."
"Compare these two revisions and flag what needs rechecking before tooling."
"Which holes are blind vs through? What's the depth of the blind hole?"
"Find the thinnest wall section on this part. Is it above the 1.5mm minimum?"

See docs/EXAMPLE_PROMPTS.md for more.

Requirements

Node.js 24+
STEP files (export from SolidWorks, FreeCAD, Fusion 360, CATIA, or any CAD system)

License

MIT. The bundled OCCT kernel uses LGPL-2.1. See THIRD_PARTY_NOTICES.md.