update_webhook · Posteverywhere MCP: Risk & Policy

WHAT IT DOES

What update_webhook does on Posteverywhere

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

WHY IT NEEDS A POLICY

Why update_webhook needs a policy

This tool creates or modifies webhook configurations reversibly. While webhooks can trigger external operations, the update_webhook tool itself only modifies webhook metadata and state—it does not execute commands or trigger operations. The change is reversible (settings can be changed again), making it Write rather than Execute or Destructive.

From the tool's definition Tool description explicitly states: 'Update a webhook subscription' with ability to 'change url/events/name/description/is_active'. This modifies configuration state reversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_webhook Rate-limited

update_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": {
    "update_webhook": {
      "limits": [
        {
          "counter": "update_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 Posteverywhere, so you can run agents against it safely.

FAQ

Questions about update_webhook

What does the update_webhook tool do? +

Update a webhook subscription on PostEverywhere — change url/events/name/description/is_active. Setting is_active=true on an auto-disabled webhook clears the consecutive_failures counter. It is categorised as a Write tool in the Posteverywhere MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_webhook? +

Register the Posteverywhere MCP server in PolicyLayer and add a rule for update_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 Posteverywhere. Nothing to install.

What risk level is update_webhook? +

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

Can I rate-limit update_webhook? +

Yes. Add a rate_limit block to the update_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 update_webhook completely? +

Set action: deny in the PolicyLayer policy for update_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 update_webhook? +

update_webhook is provided by the Posteverywhere MCP server (posteverywhere/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.