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OCCTMCP

OCCTMCP documentation

An MCP server that gives LLMs the ability to author, inspect, measure and iterate on 3D CAD models with OpenCASCADE via the OCCTSwift family. The LLM picks a typed tool; OCCTMCP runs the OCCT operation in-process and writes BREP / STEP / PNG + a manifest.json scene the viewer auto-reloads.

// boolean_op — subtract one scene body from another
{ "op": "subtract", "aBodyId": "block", "bBodyId": "pin", "outputBodyId": "result" }

Two interchangeable servers read/write the same scene:

  • Swift (occtmcp-server) — the primary, in-process server. 59 typed tools. macOS 15+.
  • Node (dist/index.js) — shells out to the occtkit CLI. 37-tool subset (selection / remap / annotations / reconstruction are Swift-only). Runs anywhere Node 18+ does.

For geometry the typed tools don’t cover, the LLM falls back to execute_script: arbitrary Swift against the full OCCTSwift API, compiled and run in-process.

Cookbook

Task-oriented recipes — prose plus the actual tool calls (arguments + example results), chained into real workflows, with render_preview figures. The Cookbook index lists all areas:

Authoring · Scene & appearance · Construction · Inspection · Measurement & verification · Selection & remap · Annotations & preview · Import / export · Meshing & drawings · Healing · Topology graph · Reconstruction

Reference

  • Tool Reference — per-tool-family detail: every tool’s JSON-Schema parameters, returns, an example call + result, Node availability, and the OCCTSwift / occtkit behind it.
  • README tool table — the one-line catalog.

Guides & concepts

  • Getting started — install, wire up .mcp.json, make your first call.
  • Architecture — the two servers, the manifest scene model, history & remap, the layered OCCTSwift ecosystem.

Project