run_gcode_program · Cnc Fluidnc MCP: Risk & Policy

WHAT IT DOES

What run_gcode_program does on Cnc Fluidnc

AI agents invoke run_gcode_program to trigger actions in Cnc Fluidnc. 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 run_gcode_program needs a policy

This tool executes code (G-code programs) on a CNC router, triggering physical machinery operations. While the confirm=true requirement provides a safeguard, the tool's core function is to run arbitrary programs on external hardware with effects determined by user-supplied arguments.

From the tool's definition Tool description states 'Send a multi-line G-code program to the machine' - G-code programs control CNC router operations (cutting, drilling, movement) with irreversible physical consequences.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

run_gcode_program Rate-limited

run_gcode_program 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": {
    "run_gcode_program": {
      "limits": [
        {
          "counter": "run_gcode_program_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 Cnc Fluidnc, so you can run agents against it safely.

FAQ

Questions about run_gcode_program

What does the run_gcode_program tool do? +

Send a multi-line G-code program to the machine, one line at a time. Requires confirm=true. It is categorised as a Execute tool in the Cnc Fluidnc MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on run_gcode_program? +

Register the Cnc Fluidnc MCP server in PolicyLayer and add a rule for run_gcode_program: 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 Cnc Fluidnc. Nothing to install.

What risk level is run_gcode_program? +

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

Can I rate-limit run_gcode_program? +

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

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

run_gcode_program is provided by the Cnc Fluidnc MCP server (whitneydesignlabs/cnc-fluidnc-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.