stop_execution · N8n MCP: Risk & Policy

WHAT IT DOES

What stop_execution does on N8n

AI agents invoke stop_execution to trigger actions in N8n. 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 stop_execution needs a policy

This tool triggers an external operation (stopping an n8n workflow execution) whose effects depend on which execution is targeted. While it doesn't create, modify, or delete data permanently, it actively interrupts running automation processes, which constitutes an Execute action.

From the tool's definition The tool 'stop_execution' is designed to stop a running execution in n8n workflows. It requires write_mode, indicating it performs state-changing operations that affect active processes.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

stop_execution Rate-limited

stop_execution 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": {
    "stop_execution": {
      "limits": [
        {
          "counter": "stop_execution_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 N8n, so you can run agents against it safely.

FAQ

Questions about stop_execution

What does the stop_execution tool do? +

Stop a running execution. Requires write_mode. It is categorised as a Execute tool in the N8n MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on stop_execution? +

Register the N8n MCP server in PolicyLayer and add a rule for stop_execution: 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 N8n. Nothing to install.

What risk level is stop_execution? +

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

Can I rate-limit stop_execution? +

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

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

stop_execution is provided by the N8n MCP server (siddharth0903/n8n-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.