postprocess_gcode · Prusa MCP: Risk & Policy

WHAT IT DOES

What postprocess_gcode does on PrusaMCP

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

WHY IT NEEDS A POLICY

Why postprocess_gcode needs a policy

This tool modifies an existing G-code file by inserting actions into it. G-code directly controls 3D printer hardware movements, temperatures, and operations. Modifying G-code is a Write operation (reversible file modification), but carries high severity because malicious or incorrect G-code modifications could damage the printer, ruin prints, or in extreme cases cause hardware damage (e.g., thermal runaway).

From the tool's definition "Modifie un fichier G-code existant pour insérer des actions" (Modifies an existing G-code file to insert actions)

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

postprocess_gcode Rate-limited

postprocess_gcode 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": {
    "postprocess_gcode": {
      "limits": [
        {
          "counter": "postprocess_gcode_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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

FAQ

Questions about postprocess_gcode

What does the postprocess_gcode tool do? +

Modifie un fichier G-code existant pour insérer des actions :. It is categorised as a Write tool in the PrusaMCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on postprocess_gcode? +

Register the Prusa MCP server in PolicyLayer and add a rule for postprocess_gcode: 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 PrusaMCP. Nothing to install.

What risk level is postprocess_gcode? +

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

Can I rate-limit postprocess_gcode? +

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

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

postprocess_gcode is provided by the Prusa MCP server (noosbai/prusamcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.