clear_hms_errors · Bambu Printer MCP: Risk & Policy

WHAT IT DOES

What clear_hms_errors does on Bambu Printer

AI agents invoke clear_hms_errors to trigger actions in Bambu Printer. 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 clear_hms_errors needs a policy

This tool triggers an external operation on a physical device (Bambu Lab printer) via MQTT command to clear error states. It is not purely reading data, and while it modifies printer state, it does so by sending a command that triggers an action on the printer. The effect is resetting/clearing error flags which could allow a printer to resume operation unexpectedly, making it an Execute-category action.

From the tool's definition Clear HMS or print error state on the Bambu Lab printer using the clean_print_error MQTT command

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

clear_hms_errors Rate-limited

clear_hms_errors 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": {
    "clear_hms_errors": {
      "limits": [
        {
          "counter": "clear_hms_errors_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 Bambu Printer, so you can run agents against it safely.

FAQ

Questions about clear_hms_errors

What does the clear_hms_errors tool do? +

Clear HMS or print error state on the Bambu Lab printer using the clean_print_error MQTT command. It is categorised as a Execute tool in the Bambu Printer MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on clear_hms_errors? +

Register the Bambu Printer MCP server in PolicyLayer and add a rule for clear_hms_errors: 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 clear_hms_errors? +

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

Can I rate-limit clear_hms_errors? +

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

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

clear_hms_errors 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.