slice_stl · FreeCAD MCP: Risk & Policy

WHAT IT DOES

What slice_stl does on FreeCAD MCP

AI agents invoke slice_stl to trigger actions in FreeCAD MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why slice_stl needs a policy

Based on the server description mentioning '3D printing slicing' and the tool name 'slice_stl', this tool likely processes an STL file through a slicer to generate printer instructions (e.g., G-code). This is an Execute-level operation as it triggers an external processing pipeline. However, the empty description significantly lowers confidence. It could also be Write if it simply converts/saves a file.

From the tool's definition Tool name 'slice_stl' suggests slicing an STL file for 3D printing, which is an operation that processes/transforms a file. Description is empty and uninformative.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

slice_stl Rate-limited

slice_stl stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "slice_stl": {
      "limits": [
        {
          "counter": "slice_stl_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-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 slice_stl

What does the slice_stl tool do? +

slice_stl. It is categorised as a Execute tool in the FreeCAD MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on slice_stl? +

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

slice_stl is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit slice_stl? +

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

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

slice_stl 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.