wait_for_message · Mcp Coordinator MCP: Risk & Policy

WHAT IT DOES

What wait_for_message does on Mcp Coordinator

AI agents invoke wait_for_message to trigger actions in Mcp Coordinator. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why wait_for_message needs a policy

This tool executes a blocking operation that suspends execution pending external message receipt. While it doesn't directly modify data or issue destructive commands, it represents an Execute-category action because it controls execution flow and triggers behavior dependent on external events (MQTT message arrival).

From the tool's definition The tool description states it 'Block[s] until an MQTT consultation message arrives or timeout', indicating it performs a blocking operation that waits for external message arrival and can alter program flow control based on timing and external events.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

wait_for_message Rate-limited

wait_for_message stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "wait_for_message": {
      "limits": [
        {
          "counter": "wait_for_message_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-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 Coordinator, so you can run agents against it safely.

FAQ

Questions about wait_for_message

What does the wait_for_message tool do? +

Block until an MQTT consultation message arrives or timeout. It is categorised as a Execute tool in the Mcp Coordinator MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on wait_for_message? +

Register the Mcp Coordinator MCP server in PolicyLayer and add a rule for wait_for_message: 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 Coordinator. Nothing to install.

What risk level is wait_for_message? +

wait_for_message is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit wait_for_message? +

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

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

wait_for_message is provided by the Mcp Coordinator MCP server (swoofer/mcp-coordinator). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.