ParCAD — Claude Code MCP server: parametric CAD as code
Turns a JS script into a 3D part on the exact OpenCASCADE kernel, then hands the agent volumes, wall thickness and section views over MCP.
Open on GitHubWhat ParCAD does
Your script builds a small JSON graph of operations — box, union, cylinder, fillet — and an exact kernel reads it. That gives real faces and edges, STEP export, and a refusal instead of an approximation when something cannot be done faithfully.
Edges are picked by description, not by index: the circular rims opening onto the top face stay selected after you move a hole. .expect({ count: 4 }) turns a selector that quietly starts matching three edges into a build error. That is where CadQuery, build123d and OpenSCAD tend to bite later, when a stale selector slips through.
Version 0.0.13 is experimental and the DSL still shifts. Every build is checked against measured geometry, yet the kernel has not had years of abuse behind it: measure a part before you machine it. On macOS or Linux, Homebrew installs the host without a window.
What it helps with
- Build a bracket from a script and export STEP
- Confirm that two bores actually meet inside the part
- Catch a broken edge selector at build time
- Read internal cavities from sections drawn at one scale
- Get part measurements to an agent with no screen
Example prompts for the agent
- Build the bracket from
examples/bracket.jsand report its volume - Check the flange wall thickness and point out where it falls short
- Cut the part open and send me a view with faces labelled by tag
How to install ParCAD
Install
The MCP registry has no launch command for it: see the repository README
Step by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about ParCAD
How do I install ParCAD on macOS or Linux?
Run brew tap ierehon1905/parcad, then brew trust ierehon1905/parcad, then brew install parcad. Next, register it with your agent, which starts ParCAD when needed.
What does ParCAD do?
It builds parametric 3D parts from a JS script on the OpenCASCADE kernel, measures them, and serves the model and measurements to an agent over MCP.
How is ParCAD different from CadQuery or OpenSCAD?
Edge selection is descriptive and checked, so a miss fails the build. The preview, the measurements and the STEP file all come from one B-rep model.
