cancel_server · Llauncher MCP: Risk & Policy

WHAT IT DOES

What cancel_server does on Llauncher

AI agents invoke cancel_server to trigger actions in Llauncher. 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 cancel_server needs a policy

This tool interrupts/cancels an ongoing operation (start or swap of a server instance). It triggers an external operation that affects running processes, making it Execute. It is not purely destructive (no data deletion) but has real side effects on server lifecycle state. Misuse could abort legitimate inference server operations, causing service disruption.

From the tool's definition Cancel an in-flight start or swap on this port

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

cancel_server Rate-limited

cancel_server 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": {
    "cancel_server": {
      "limits": [
        {
          "counter": "cancel_server_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 Llauncher, so you can run agents against it safely.

FAQ

Questions about cancel_server

What does the cancel_server tool do? +

Cancel an in-flight start or swap on this port (ADR-014). It is categorised as a Execute tool in the Llauncher MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on cancel_server? +

Register the Llauncher MCP server in PolicyLayer and add a rule for cancel_server: 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 Llauncher. Nothing to install.

What risk level is cancel_server? +

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

Can I rate-limit cancel_server? +

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

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

cancel_server is provided by the Llauncher MCP server (shanevcantwell/llauncher). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.