Yes. It is open source on GitHub and installs with pip install mesh2cad from PyPI.
No. Planes, cylinders, cones, spheres and fillets are fitted and written as an exact B-rep, so holes and faces can be selected and dimensioned in CAD. If no exact fit passes, it falls back to a faceted solid and says so in the report.
Every parametric export is checked against the input mesh: maximum deviation must be at most max(4 x tolerance, 0.1 mm) and volume error at most 1%. The --report file lists the measured numbers.
Mechanical parts made of planes, cylinders, cones, chamfers and simple fillets. On 6 real Original Prusa i3 MK3S parts: exact STEP for 6 of 6, editable CadQuery/OpenSCAD for 6 of 6.
Organic shapes, 3D scans and freeform (B-spline) surfaces. In the Prusa test set all six parts now export scripts, but the small B-spline patches on y-belt-holder are still approximated by the section the mesh has at each station. Fillets on hole edges (torus) are not supported yet.
Yes. pip install "mesh2cad[mcp]" and add { "mcpServers": { "mesh2cad": { "command": "mesh2cad", "args": ["mcp"] } } } to the client config. Tools: convert, analyze, report, to_cadquery, to_openscad.
Only to verify .scad output. The script is still written without it.
Open an issue on GitHub with the file. Failing real parts are the most useful input.
mesh2cad is free and open source (see the GitHub repository for the license). Found an STL it handles badly? Open an issue with the file.