create_shape · FreeCAD MCP: Risk & Policy

WHAT IT DOES

What create_shape does on FreeCAD MCP

AI agents use create_shape 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 create_shape needs a policy

This tool creates new CAD objects/shapes within FreeCAD, which is reversible (shapes can be deleted or modified). It does not destructively delete data, execute arbitrary code, or trigger external operations with unpredictable effects. Classification as Write is appropriate for CAD object creation.

From the tool's definition Tool name 'create_shape' in FreeCAD MCP context suggests creation of CAD geometry. Sibling tools like 'bim_create_column', 'bim_create_door', 'bim_create_wall' all perform reversible object creation within a CAD design project.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_shape Rate-limited

create_shape 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": {
    "create_shape": {
      "limits": [
        {
          "counter": "create_shape_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

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 create_shape

What does the create_shape tool do? +

create_shape. 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 create_shape? +

Register the FreeCAD MCP server in PolicyLayer and add a rule for create_shape: 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 create_shape? +

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

Can I rate-limit create_shape? +

Yes. Add a rate_limit block to the create_shape 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 create_shape completely? +

Set action: deny in the PolicyLayer policy for create_shape. 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 create_shape? +

create_shape 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.