CAD MCP Server

What CAD MCP Server MCP server does

The CAD MCP Server MCP server gives an AI assistant structured access to STEP CAD geometry through MCP. It can inspect a part or assembly, locate geometric entities, run measurements, and compare two STEP revisions. Supported analysis includes overall dimensions, volume, surface area, body structure, assembly structure, B-rep health, cylindrical features, wall thickness, clearance, draft, cross-sections, and edge continuity.

The server reads the model's own B-rep geometry rather than relying on an image or screenshot. Open CASCADE performs the geometric calculations. Length results use millimetres, and angular results use degrees.

How it works

Add the server as an MCP process, then provide the assistant with a path to a STEP file. Processing occurs locally over standard input and output. The server reads files without writing to the CAD data, and it does not require a separate CAD application or license.

Each inspection produces a revision-bound reference. Measurement results include the relevant entity IDs and the SHA-256 revision associated with the source file. If a file changes during a session, stale entity IDs are rejected instead of being silently applied to a different revision.

The CAD MCP Server MCP server accepts STEP files exported by systems including SolidWorks, Fusion 360, Onshape, FreeCAD, and CATIA, as well as STEP files from other CAD systems.

Setup and configuration

The documented quick-start configuration uses Node.js and npx:

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

The runtime requirement is Node.js 24 or newer. Supported platforms are Windows x64, macOS ARM64 on Apple Silicon, and Linux x64. After adding the process to an MCP client, direct the assistant to a STEP file and ask for the required analysis.

Tools and capabilities

• inspect returns bounding-box dimensions, volume, surface area, body and assembly structure, B-rep health, and a revision-bound reference.
• find_entities searches faces, edges, vertices, and bodies. Filters include surface type, radius, axis, and area.
• measure supports face-to-face distance, wall thickness, draft, ray casts, ray grids, point analysis, planar sections, and edge continuity. Measurement kinds are distance, thickness, draft, ray, ray_grid, point_analysis, section, and continuity.
• diff compares two STEP revisions for dimension, volume, area, and topology changes, and returns parsed STEP metadata.

Typical requests include finding cylindrical faces and their diameters, checking the distance from a hole to a wall, measuring draft along the positive Z direction, sectioning a body at a coordinate, or identifying changes between revisions.

Limitations and notes

The CAD MCP Server MCP server reports geometry and does not determine whether a part is manufacturable; that conclusion remains an engineering judgment. It is read-only and processes files locally, but STEP input should still be treated as sensitive CAD data. The project is MIT licensed, while its bundled Open CASCADE sidecar uses LGPL-2.1.