mqtt_publish · Mcp Coordinator MCP: Risk & Policy

WHAT IT DOES

What mqtt_publish does on Mcp Coordinator

AI agents invoke mqtt_publish 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 mqtt_publish needs a policy

Publishing to MQTT is an external side-effecting operation: it dispatches a message to a broker which may trigger subscribers, automation systems, or other agents. This goes beyond a simple write (local data creation/modification) into executing an external communication/event trigger.

From the tool's definition 'Publish a message to an MQTT topic' — triggers an external operation by sending a message to an MQTT broker, whose effects depend on the topic and payload arguments

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mqtt_publish Rate-limited

mqtt_publish 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": {
    "mqtt_publish": {
      "limits": [
        {
          "counter": "mqtt_publish_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 mqtt_publish

What does the mqtt_publish tool do? +

Publish a message to an MQTT topic. 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 mqtt_publish? +

Register the Mcp Coordinator MCP server in PolicyLayer and add a rule for mqtt_publish: 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 mqtt_publish? +

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

Can I rate-limit mqtt_publish? +

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

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

mqtt_publish 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.