mqtt_unsubscribe · MQTT MCP Server MCP: Risk & Policy

WHAT IT DOES

What mqtt_unsubscribe does on MQTT MCP Server

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

WHY IT NEEDS A POLICY

Why mqtt_unsubscribe needs a policy

Unsubscribing modifies the client's subscription state by removing a topic subscription. This is a Write operation because it changes configuration/state, but reversibly (the client can re-subscribe). It has low severity because it only affects the calling client's own subscriptions with no blast radius to other systems, data integrity, or irreversible consequences.

From the tool's definition Tool name 'mqtt_unsubscribe' and description 'Unsubscribe from an MQTT topic' indicate modification of subscription state. The action removes an active subscription, which is a reversible state change to the client's connection configuration.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

mqtt_unsubscribe Rate-limited

mqtt_unsubscribe 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": {
    "mqtt_unsubscribe": {
      "limits": [
        {
          "counter": "mqtt_unsubscribe_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about mqtt_unsubscribe

What does the mqtt_unsubscribe tool do? +

Unsubscribe from an MQTT topic. It is categorised as a Write tool in the MQTT 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 mqtt_unsubscribe? +

Register the MQTT MCP Server MCP server in PolicyLayer and add a rule for mqtt_unsubscribe: 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 MQTT MCP Server. Nothing to install.

What risk level is mqtt_unsubscribe? +

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

Can I rate-limit mqtt_unsubscribe? +

Yes. Add a rate_limit block to the mqtt_unsubscribe 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_unsubscribe completely? +

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

mqtt_unsubscribe is provided by the MQTT MCP Server MCP server (sergiudanstan/mqtt-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.