FreeCAD MCP bridge (blwfish/freecad-mcp) errors

5 recurring problems engineers report in FreeCAD MCP bridge (blwfish/freecad-mcp), ranked by impact.

#110 by errors trackedMCAD

Recurring FreeCAD MCP bridge (blwfish/freecad-mcp) errors, by impact

  1. 1A FreeCAD MCP bridge silently ignored parameters the client materialized from JSON-Schema defaults, so box(size=20) produced a default 10mm shape. The agent believes it built the requested geometry while the model is something else entirely.MCAD · Agent failure · 1 report56
  2. 2A FreeCAD MCP bridge's autosave-before-call rewrote the active document on every tool call even with zero unsaved changes, stamping phantom diffs onto git-tracked CAD files. Agent activity pollutes version control with edits no human authored.MCAD · Agent failure · 1 report46
  3. 3A CAD agent bridge's screenshot tool refused any image over a 50KB socket frame, so every real model screenshot was dropped, and images that did fit arrived as base64 text inside JSON instead of real image blocks. The agent's only visual feedback channel was dead for production-scale models.MCAD · Agent failure · 1 report44
  4. 4A FreeCAD MCP bridge's persistent execution namespace meant that once any call bound a variable named result, every later call echoed the old value as its own output. The agent reads that output and believes its code produced a value it never computed.MCAD · Agent failure · 1 report44
  5. 5A FreeCAD MCP bridge reported clean instance shutdowns as failures 100 percent of the time on Linux, because its liveness check polled immediately after signaling the process group. The agent was sent to retry or kill processes that were already gone.MCAD · Agent failure · 1 report41

How it fails

  1. Agent failure5

Engineering tools that address these errors

Sourced from public community reports. Costs and delays on individual entries are modeled estimates, not measurements.