mqtt_publish · MCP API Bridge Server MCP: Risk & Policy

WHAT IT DOES

What mqtt_publish does on MCP API Bridge Server

AI agents invoke mqtt_publish to trigger actions in MCP API Bridge Server. 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 MQTT messages triggers real-time actions on IoT devices and systems. The effects depend entirely on the message payload and topic — ranging from benign status updates to controlling physical devices (actuators, switches, industrial equipment). This is an Execute-category action because it initiates external operations whose consequences are payload-dependent and can have significant physical-world effects.

From the tool's definition '發布 MQTT 訊息' (Publish MQTT message) — triggers external operations by sending messages to IoT devices/systems via MQTT broker

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 API Bridge Server, so you can run agents against it safely.

FAQ

Questions about mqtt_publish

What does the mqtt_publish tool do? +

發布 MQTT 訊息. It is categorised as a Execute tool in the MCP API Bridge Server 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 API Bridge Server 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 API Bridge Server. 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 API Bridge Server MCP server (marty5499/mcp-api-bridge). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.