create_webhook · Campaign Monitor MCP: Risk & Policy

WHAT IT DOES

What create_webhook does on Campaign Monitor MCP

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

WHY IT NEEDS A POLICY

Why create_webhook needs a policy

Creating a webhook modifies the system configuration by adding a new event notification endpoint. This is a reversible Write operation (webhooks can be deleted or reconfigured). It carries medium severity because misconfiguration could route sensitive subscriber data to attacker-controlled endpoints, but the action itself is not destructive and does not directly access financial systems.

From the tool's definition Tool name 'create_webhook' and description 'Create a webhook for a subscriber list' indicate creation of a new webhook configuration, which is a reversible write operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_webhook Rate-limited

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.

View as policy code

policy.json

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

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Instant setup, no code required.

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

FAQ

Questions about create_webhook

What does the create_webhook tool do? +

Create a webhook for a subscriber list. It is categorised as a Write tool in the Campaign Monitor 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 create_webhook? +

Register the Campaign Monitor 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 Campaign Monitor MCP. 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 Campaign Monitor MCP server (pauliowest/cmon-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.