book_flight · LetsFG MCP: Risk & Policy

WHAT IT DOES

What book_flight does on LetsFG

AI agents use book_flight to commit financial operations through LetsFG — usually the final step of a payment, billing, or trading workflow. A call moves real money.

WHY IT NEEDS A POLICY

Why book_flight needs a policy

Booking a flight creates a real reservation (PNR) with financial consequences: payment is charged and a legal travel contract is formed. This is a Financial action with critical severity because an AI agent misusing this tool could make irreversible, costly bookings on behalf of users.

From the tool's definition "Book an unlocked flight — creates real airline reservation with PNR" — commits a real airline booking and financial obligation

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

book_flight Approval-gated

Any call to book_flight is blocked until a human approves it. The rest of the server keeps working.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "book_flight": {
      "deny_if": [
        {
          "conditions": [],
          "on_deny": "Requires human approval."
        }
      ]
    }
  }
}

GATE THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about book_flight

What does the book_flight tool do? +

Book an unlocked flight — creates real airline reservation with PNR (step 3 of 3). Developer API only.\n\n. It is categorised as a Financial tool in the LetsFG MCP Server, which means it involves financial transactions. Block by default and require explicit approval.

How do I enforce a policy on book_flight? +

Register the LetsFG MCP server in PolicyLayer and add a rule for book_flight: 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 LetsFG. Nothing to install.

What risk level is book_flight? +

book_flight is a Financial tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit book_flight? +

Yes. Add a rate_limit block to the book_flight 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_flight completely? +

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

book_flight is provided by the LetsFG MCP server (letsfg/letsfg). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.