cad-mcp-server

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

npx -y cad-mcp-server

Add to your MCP client:

{
  "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?"
query_faces	"Find all cylindrical faces. Which ones are holes vs bosses?"
query_edges	"What's the smallest fillet radius on this part?"
measure_step	"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 22+
• 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.