agentcad

agentcad is a CAD command-line tool and MCP server that gives AI coding agents the ability to design 3D models. The agent writes build123d Python scripts by default, and agentcad handles execution, STEP export, PNG rendering, mesh export (STL, GLB, OBJ), geometric metrics, validation, diffing, and browser preview. CadQuery remains available as an explicit compatibility mode, and each command's final response is structured JSON on stdout.

The required agent workflow is Inspect, Specify, Build, Validate, Deliver, installed as a guide by agentcad init. It runs locally with no signup, installs with pip, and ships a reusable agent skill separately through the Skills CLI or ClawHub. The v0.7.0 release brought a five-stage workflow to the installed guide and built-in help.

The README reports a CADGenBench comparison in which GPT-5 Nano using agentcad scored 48 percent higher on CAD Score at 21.8 percent lower model cost than a direct build123d baseline, and produced 2.5 times as many valid outputs. The README itself cautions that the cited Candidate L run is a single run, not a new matched direct-build123d comparison, and points to an experiment closeout document for the baseline and caveats.