publish_mqtt_data · CO2 Sensor MCP Server MCP: Risk & Policy

WHAT IT DOES

What publish_mqtt_data does on CO2 Sensor MCP Server

AI agents use publish_mqtt_data to create or update resources in CO2 Sensor MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your CO2 Sensor MCP Server environment.

WHY IT NEEDS A POLICY

Why publish_mqtt_data needs a policy

Publishing sensor data to MQTT is a write operation that modifies the state of an external message broker by adding data to a topic. While not destructive or financial, it represents a side effect that could trigger downstream systems consuming that MQTT topic. The tool is currently unimplemented, which slightly reduces severity, but the capability remains a write action.

From the tool's definition Tool name 'publish_mqtt_data' and description indicate it sends/publishes data to an external MQTT broker. Publishing is a write operation that transmits data to an external system.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

publish_mqtt_data Rate-limited

publish_mqtt_data 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": {
    "publish_mqtt_data": {
      "limits": [
        {
          "counter": "publish_mqtt_data_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches CO2 Sensor MCP Server, so you can run agents against it safely.

FAQ

Questions about publish_mqtt_data

What does the publish_mqtt_data tool do? +

Publish current sensor data to the MQTT topic (NOT IMPLEMENTED). It is categorised as a Write tool in the CO2 Sensor MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on publish_mqtt_data? +

Register the CO2 Sensor MCP Server MCP server in PolicyLayer and add a rule for publish_mqtt_data: 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 CO2 Sensor MCP Server. Nothing to install.

What risk level is publish_mqtt_data? +

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

Can I rate-limit publish_mqtt_data? +

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

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

publish_mqtt_data is provided by the CO2 Sensor MCP Server MCP server (kmwebnet/mcp-server-for-sensor-device). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.