get_webhook_url

THE RISK

Low Risk

Why get_webhook_url needs a policy

The tool retrieves information about an existing webhook endpoint without creating, modifying, deleting, or executing anything. The optional validation is a passive check. This is clearly a Read operation with low severity as it only exposes pre-existing webhook URLs without side effects.

From the tool's definition Tool name and description indicate retrieval of a webhook URL: 'Get the full URL for a webhook token. Optionally validate that the token exists.' This is a query operation with no modification, deletion, or execution of code.

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

POLICY

How to control get_webhook_url

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 get_webhook_url:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_webhook_url": {}
  }
}

get_webhook_url is read-only, so it stays allowed — but 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.

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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 Create a new webhook.site endpoint. Returns the unique token/URL for the webhook.

All 23 Webhook Site MCP Server tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about get_webhook_url

What does the get_webhook_url tool do? +

Get the full URL for a webhook token. Optionally validate that the token exists. It is categorised as a Read tool in the Webhook Site MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on get_webhook_url? +

Register the Webhook Site MCP Server MCP server in PolicyLayer and add a rule for get_webhook_url: 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 get_webhook_url? +

get_webhook_url is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit get_webhook_url? +

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

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

get_webhook_url 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 →