ams_unload_filament

THE RISK

High Risk

Why ams_unload_filament needs a policy

This tool triggers a physical hardware operation on the 3D printer — mechanically retracting filament from the extruder. It is an external physical action with real-world effects (interrupting a print, requiring manual re-loading), but it is not strictly irreversible (filament can be reloaded). It falls under Execute as it triggers an external hardware operation whose effects depend on printer state.

From the tool's definition Unload the current filament from the extruder

Documented attack patterns abuse exactly the kind of access ams_unload_filament gives an agent:

POLICY

How to control ams_unload_filament

PolicyLayer is an MCP gateway — it sits between your AI agents and Bambu Lab MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for ams_unload_filament:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "ams_unload_filament": {
      "limits": [
        {
          "counter": "ams_unload_filament_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

ams_unload_filament 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.

Create a free account and register Bambu Lab MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RATE-LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Bambu Lab MCP Server tools

Execute printer_print_file Start printing a file on the printer SD card (uploaded via ftp_upload_file). Execute printer_stop Stop the current print job immediately Execute ams_change_filament Change to a different AMS filament tray (0-3) Execute makerworld_print Download a model from MakerWorld and print it on the connected printer. Execute monitor_stop Stop the AI print monitor. Returns a summary of the monitoring session. Execute printer_pause Pause the current print job Execute sign_message Sign a message with X.509 certificate for authenticated printer communication. Uses the ex Execute skip_objects Skip specific objects during a multi-object print. Useful for excluding failed parts witho

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Go deeper

High-risk tools in Bambu Lab MCP Server → Every high-risk tool this server exposes, in one view.
All high-risk MCP tools → Every high-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Agent sandbox → Bounding what an agent can execute and where the boundary should sit.
Least privilege for MCP → Granting agents the minimum tool surface the task needs.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about ams_unload_filament

What does the ams_unload_filament tool do? +

Unload the current filament from the extruder. It is categorised as a Execute tool in the Bambu Lab MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on ams_unload_filament? +

Register the Bambu Lab MCP Server MCP server in PolicyLayer and add a rule for ams_unload_filament: 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 Lab MCP Server. Nothing to install.

What risk level is ams_unload_filament? +

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

Can I rate-limit ams_unload_filament? +

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

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

ams_unload_filament is provided by the Bambu Lab MCP Server MCP server (schwarztim/bambu-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Bambu Lab MCP Server tool call.

Start from Bambu Lab MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →