execution_stop · N8n Fabric MCP: Risk & Policy

WHAT IT DOES

What execution_stop does on N8n Fabric

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

Stopping a running execution is an Execute action—it triggers an external operation (halting a workflow in n8n) whose effects depend on which execution is targeted. While not destructive (the workflow data persists), it interrupts active operations and can disrupt automation pipelines. Severity is high because an agent could maliciously stop critical workflows, causing service disruption or data processing failures.

From the tool's definition Tool name is 'execution_stop' and description states 'Stop a running execution'. This directly stops/halts an executing workflow without creating or deleting resources.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

execution_stop Rate-limited

execution_stop 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": {
    "execution_stop": {
      "limits": [
        {
          "counter": "execution_stop_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 Fabric, so you can run agents against it safely.

FAQ

Questions about execution_stop

What does the execution_stop tool do? +

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

How do I enforce a policy on execution_stop? +

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

What risk level is execution_stop? +

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

Can I rate-limit execution_stop? +

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

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

execution_stop is provided by the N8n Fabric MCP server (ry-ops/n8n-fabric). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.