upload_gcode · Bambu Printer MCP: Risk & Policy

WHAT IT DOES

What upload_gcode does on Bambu Printer

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

WHY IT NEEDS A POLICY

Why upload_gcode needs a policy

This is a Write operation because it transfers/uploads a file to the printer, creating or modifying the printer's state and job queue. While G-code execution could be considered Execute, the tool itself performs the upload action (Write).

From the tool's definition Tool uploads a G-code file to the printer. G-code is executable machine instructions that control 3D printing hardware (movement, temperature, extrusion).

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

upload_gcode Rate-limited

upload_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": {
    "upload_gcode": {
      "limits": [
        {
          "counter": "upload_gcode_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

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

FAQ

Questions about upload_gcode

What does the upload_gcode tool do? +

Upload a G-code file to the Bambu Lab printer. It is categorised as a Write tool in the Bambu Printer MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on upload_gcode? +

Register the Bambu Printer MCP server in PolicyLayer and add a rule for upload_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 Bambu Printer. Nothing to install.

What risk level is upload_gcode? +

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

Can I rate-limit upload_gcode? +

Yes. Add a rate_limit block to the upload_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 upload_gcode completely? +

Set action: deny in the PolicyLayer policy for upload_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 upload_gcode? +

upload_gcode is provided by the Bambu Printer MCP server (rowbotik/bambu-printer-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.