run_webhook

THE RISK

High Risk

Why run_webhook needs a policy

This tool triggers execution of arbitrary n8n workflows with optional input parameters. The effects depend entirely on what those workflows do—they could modify data, call external APIs, delete resources, or perform financial transactions. An AI agent with access to this tool could inadvertently trigger destructive or harmful workflow executions.

From the tool's definition Tool name 'run_webhook' and description 'Execute a workflow via webhook with optional input data' indicate execution of external workflows with user-supplied input arguments.

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

POLICY

How to control run_webhook

PolicyLayer is an MCP gateway — it sits between your AI agents and n8n MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for run_webhook:

policy.json

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

run_webhook 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 n8n 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 n8n MCP Server tools

Destructive delete_execution Delete a specific workflow execution from n8n Destructive delete_workflow Delete a workflow from n8n Write deactivate_workflow Deactivate a workflow in n8n Write activate_workflow Activate a workflow in n8n Write create_workflow Create a new workflow in n8n Write update_workflow Update an existing workflow in n8n Read get_execution Retrieve detailed information about a specific workflow execution Read get_workflow Retrieve a specific workflow by ID

All 11 n8n MCP Server tools →

Execute tools on other servers

Android Forensics ADB MCP Server adb_shell_command EMBA-MCP run_emba_scan Frida Game Hacking MCP remove_breakpoint Procmon request_elevation

Go deeper

High-risk tools in n8n 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 run_webhook

What does the run_webhook tool do? +

Execute a workflow via webhook with optional input data. It is categorised as a Execute tool in the n8n 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 run_webhook? +

Register the n8n MCP Server MCP server in PolicyLayer and add a rule for run_webhook: 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 MCP Server. Nothing to install.

What risk level is run_webhook? +

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

Can I rate-limit run_webhook? +

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

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

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

Enforce policy on every n8n MCP Server tool call.

Start from n8n 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 →