create_webhook

THE RISK

Medium Risk

Why create_webhook needs a policy

Creating a webhook endpoint is a reversible write operation—it adds a new resource to the system without permanently destroying data or executing arbitrary code. Severity is medium because while webhook creation itself is benign, the tool exists within a context (Webhook.site) designed for capturing HTTP requests and potentially sensitive data, and an agent could create many endpoints or use them in phishing/data…

From the tool's definition Tool name 'create_webhook' and description 'Create a new webhook.site endpoint' indicate data creation. The tool 'Returns the unique token/URL for the webhook' confirms a new resource is being instantiated.

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

POLICY

How to control create_webhook

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

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "create_webhook": {
      "limits": [
        {
          "counter": "create_webhook_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

create_webhook stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

Create a free account and register Webhook Site 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.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Webhook Site MCP Server tools

Destructive delete_all_requests Delete all requests from a webhook, optionally filtered by date range or query. Destructive delete_request Delete a specific request from a webhook. Destructive delete_webhook Delete a webhook.site endpoint and all its data. Execute generate_ssrf_payload Generate SSRF (Server-Side Request Forgery) test payloads for bug bounty testing. Creates Execute generate_xss_callback Generate XSS (Cross-Site Scripting) callback payloads for bug bounty testing. Creates Java Execute send_multiple_requests Send multiple requests to a webhook in batch. Useful for load testing or sending multiple Execute send_to_webhook Send a POST request with JSON data to a webhook.site endpoint. Write create_webhook_with_config Create a new webhook.site endpoint with custom configuration (response content, status, ti

All 23 Webhook Site MCP Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about create_webhook

What does the create_webhook tool do? +

Create a new webhook.site endpoint. Returns the unique token/URL for the webhook. It is categorised as a Write tool in the Webhook Site MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_webhook? +

Register the Webhook Site MCP Server MCP server in PolicyLayer and add a rule for create_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 Webhook Site MCP Server. Nothing to install.

What risk level is create_webhook? +

create_webhook is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit create_webhook? +

Yes. Add a rate_limit block to the create_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 create_webhook completely? +

Set action: deny in the PolicyLayer policy for create_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 create_webhook? +

create_webhook is provided by the Webhook Site MCP Server MCP server (zebbern/webhook-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 Webhook Site MCP Server tool call.

Start from Webhook Site 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 →