book_appointment · Nexus Core MCP: Risk & Policy

WHAT IT DOES

What book_appointment does on Nexus Core

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

WHY IT NEEDS A POLICY

Why book_appointment needs a policy

Booking an appointment creates a calendar reservation, which is a Write action (creates a new record/commitment). It could have financial implications if the booking involves paid services, but there's no explicit mention of payment processing. The 'APPROVAL-GATED' flag suggests some safeguard exists, but the underlying action is still creating a commitment on behalf of the user.

From the tool's definition book_appointment — 'Calendly-style booking'; 'APPROVAL-GATED'

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

book_appointment Rate-limited

book_appointment 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": {
    "book_appointment": {
      "limits": [
        {
          "counter": "book_appointment_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 Nexus Core, so you can run agents against it safely.

FAQ

Questions about book_appointment

What does the book_appointment tool do? +

APPROVAL-GATED: Calendly-style booking. Site-specific adapters not yet wired. It is categorised as a Write tool in the Nexus Core MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on book_appointment? +

Register the Nexus Core MCP server in PolicyLayer and add a rule for book_appointment: 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 Nexus Core. Nothing to install.

What risk level is book_appointment? +

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

Can I rate-limit book_appointment? +

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

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

book_appointment is provided by the Nexus Core MCP server (noumenon-ai/nexus-core). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.