mesh_to_solid · FreeCAD MCP: Risk & Policy

WHAT IT DOES

What mesh_to_solid does on FreeCAD MCP

AI agents use mesh_to_solid to create or update resources in FreeCAD MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your FreeCAD MCP environment.

WHY IT NEEDS A POLICY

Why mesh_to_solid needs a policy

mesh_to_solid converts 3D mesh data into solid CAD models, which modifies the data structure and representation reversibly. This is a Write operation: it creates or transforms data that can be edited or reverted. While it operates on CAD files, it does not execute arbitrary code, delete data irreversibly, or cause financial impact.

From the tool's definition Tool name 'mesh_to_solid' indicates conversion/transformation of mesh geometry into solid geometry. Sibling tools show this server performs CAD operations including part conversion (e.g., bim_export_ifc, bim_import_ifc).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mesh_to_solid Rate-limited

mesh_to_solid stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "mesh_to_solid": {
      "limits": [
        {
          "counter": "mesh_to_solid_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches FreeCAD MCP, so you can run agents against it safely.

FAQ

Questions about mesh_to_solid

What does the mesh_to_solid tool do? +

mesh_to_solid. It is categorised as a Write tool in the FreeCAD MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on mesh_to_solid? +

Register the FreeCAD MCP server in PolicyLayer and add a rule for mesh_to_solid: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches FreeCAD MCP. Nothing to install.

What risk level is mesh_to_solid? +

mesh_to_solid is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit mesh_to_solid? +

Yes. Add a rate_limit block to the mesh_to_solid rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block mesh_to_solid completely? +

Set action: deny in the PolicyLayer policy for mesh_to_solid. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides mesh_to_solid? +

mesh_to_solid is provided by the FreeCAD MCP server (sandraschi/freecad-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.