MQTT MCP Server

mqtt_connect

Connect to an MQTT broker via URL, with optional client ID and authentication credentials.

Instructions

Connect to an MQTT broker

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "broker_url": "<broker_url>"
    },
    "name": "mqtt_connect"
  }
}

Input Schema

Name	Required	Description
`broker_url`	Yes	MQTT broker URL (e.g., mqtt://localhost:1883 or mqtts://broker.example.com:8883)
`client_id`	No	Optional client ID for the connection
`username`	No	Optional username for authentication
`password`	No	Optional password for authentication

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jun 24, 2026

TDQS

B3.1/5.0

Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description should disclose behaviors like connection timeout, success/failure handling, or state management. It only says 'Connect to an MQTT broker', leaving many aspects unclear.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is very concise with a single sentence. While efficient, it may be too minimal for a connection tool; however, it avoids unnecessary fluff.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's role in a suite of MQTT tools, the description lacks details about connection lifecycle, return values, and error scenarios. It does not cover the full context needed for an agent to use it correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% with descriptions for each parameter. The tool description adds no extra meaning beyond what the schema already provides, achieving the baseline for high coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action (Connect) and the resource (an MQTT broker), distinguishing it from siblings like mqtt_disconnect or mqtt_publish.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance on when to use this tool (e.g., before any other MQTT operations) or when not to (e.g., if already connected). No comparison to alternatives or prerequisites.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server