convert_currency · MCP Travel Planner MCP: Risk & Policy

WHAT IT DOES

What convert_currency does on MCP Travel Planner

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

WHY IT NEEDS A POLICY

Why convert_currency needs a policy

An AI agent can call convert_currency faster than any human can review — one bad instruction and it creates or modifies resources in MCP Travel Planner by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

convert_currency Rate-limited

convert_currency 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": {
    "convert_currency": {
      "limits": [
        {
          "counter": "convert_currency_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 MCP Travel Planner, so you can run agents against it safely.

FAQ

Questions about convert_currency

What does the convert_currency tool do? +

convert_currency. It is categorised as a Write tool in the MCP Travel Planner MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on convert_currency? +

Register the MCP Travel Planner MCP server in PolicyLayer and add a rule for convert_currency: 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 MCP Travel Planner. Nothing to install.

What risk level is convert_currency? +

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

Can I rate-limit convert_currency? +

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

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

convert_currency is provided by the MCP Travel Planner MCP server (leonavevor/mcp_travelassistant). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.