mqtt_register_handler · MCP API Bridge Server MCP

WHAT IT DOES

What mqtt_register_handler does on MCP API Bridge Server

AI agents invoke mqtt_register_handler 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_register_handler needs a policy

Registering a message handler sets up executable logic that will run automatically upon receiving MQTT messages. This is an Execute-category action because it triggers external operations and runs handler code whose effects depend on the registered logic and incoming message arguments. Misuse could cause unintended automated actions across IoT devices at scale, warranting high severity.

From the tool's definition 'mqtt_register_handler' — '註冊 MQTT 訊息處理器' translates to 'Register MQTT message handler', indicating the tool registers a callback/handler that executes code or logic when MQTT messages are received

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mqtt_register_handler Rate-limited

mqtt_register_handler 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_register_handler": {
      "limits": [
        {
          "counter": "mqtt_register_handler_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_register_handler

What does the mqtt_register_handler tool do? +

註冊 MQTT 訊息處理器. 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_register_handler? +

Register the MCP API Bridge Server MCP server in PolicyLayer and add a rule for mqtt_register_handler: 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_register_handler? +

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

Can I rate-limit mqtt_register_handler? +

Yes. Add a rate_limit block to the mqtt_register_handler 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_register_handler completely? +

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

mqtt_register_handler 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.