register_webhook · Tenzro Ledger MCP: Risk & Policy

WHAT IT DOES

What register_webhook does on Tenzro Ledger MCP

AI agents use register_webhook to create or update resources in Tenzro Ledger MCP — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Tenzro Ledger MCP environment.

WHY IT NEEDS A POLICY

Why register_webhook needs a policy

Registering a webhook is a write operation that creates or modifies system configuration (the webhook entry itself). It is reversible (webhooks can be deleted or updated) and does not directly move money, execute arbitrary code, or delete data. However, severity is elevated to medium due to the implicit trust boundary: a malicious webhook URL could receive sensitive event notifications, potentially exfiltrating data.

From the tool's definition Tool name 'register_webhook' and description 'Register a webhook URL to receive event notifications' indicate creation/modification of a webhook configuration. This is a reversible write operation that stores a new callback URL in the system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

register_webhook Rate-limited

register_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.

View as policy code

policy.json

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

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Tenzro Ledger MCP, so you can run agents against it safely.

FAQ

Questions about register_webhook

What does the register_webhook tool do? +

Register a webhook URL to receive event notifications. It is categorised as a Write tool in the Tenzro Ledger MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on register_webhook? +

Register the Tenzro Ledger MCP server in PolicyLayer and add a rule for register_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 Tenzro Ledger MCP. Nothing to install.

What risk level is register_webhook? +

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

Can I rate-limit register_webhook? +

Yes. Add a rate_limit block to the register_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 register_webhook completely? +

Set action: deny in the PolicyLayer policy for register_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 register_webhook? +

register_webhook is provided by the Tenzro Ledger MCP server (https://canton-mcp.tenzro.network/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.