send_gcode · Kiln MCP: Risk & Policy

WHAT IT DOES

What send_gcode does on Kiln

AI agents invoke send_gcode to trigger actions in Kiln. 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 send_gcode needs a policy

Sending GCode to a 3D printer executes arbitrary machine instructions that control physical actuators. Misuse could cause hardware damage (overheating, motor crashes), fire hazards, or destruction of prints and equipment. The description is empty, but the tool name in context of a 3D printer control server makes the function clear.

From the tool's definition Tool name 'send_gcode' on a server described as 'AI agent control of 3D printers'. GCode is a command language that directly controls physical hardware (movement, temperature, extrusion, fans, etc.).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_gcode Rate-limited

send_gcode 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": {
    "send_gcode": {
      "limits": [
        {
          "counter": "send_gcode_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 Kiln, so you can run agents against it safely.

FAQ

Questions about send_gcode

What does the send_gcode tool do? +

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

How do I enforce a policy on send_gcode? +

Register the Kiln MCP server in PolicyLayer and add a rule for send_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 Kiln. Nothing to install.

What risk level is send_gcode? +

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

Can I rate-limit send_gcode? +

Yes. Add a rate_limit block to the send_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 send_gcode completely? +

Set action: deny in the PolicyLayer policy for send_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 send_gcode? +

send_gcode is provided by the Kiln MCP server (codeofaxel/Kiln). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.