Bambu Lab MCP Server

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mqtt_connect

Establish a secure MQTT connection to a Bambu Lab 3D printer for local control and monitoring. Required before sending printer commands.

Instructions

Connect to a Bambu Lab printer via local MQTT over TLS. Required before any printer control commands.

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": {
      "host": "<host>",
      "password": "<password>",
      "device_id": "<device_id>"
    },
    "name": "mqtt_connect"
  }
}

Input Schema

Name	Required	Description
`host`	Yes	Printer IP address
`port`	No	MQTT port (default: 8883)
`username`	No	MQTT username (default: "bblp")
`password`	Yes	LAN access code from printer screen
`device_id`	Yes	Printer serial number

Schema Changelog

Changes observed during successful MCP inspections.

First observedv3.0.0Feb 6, 2026

TDQS

A4.2/5.0

Behavior3/5

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

With no annotations provided, the description carries full burden. It discloses the connection purpose and prerequisite behavior, but lacks details about connection persistence, error handling, timeout behavior, or authentication requirements beyond password. It doesn't contradict any annotations.

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

Conciseness5/5

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

Two sentences with zero waste. The first sentence states the core purpose and method, the second provides critical usage context. Every word earns its place in this efficiently structured description.

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

Completeness4/5

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

For a connection tool with no annotations and no output schema, the description adequately covers the purpose and prerequisite context. However, it lacks information about what happens after connection (e.g., connection state management, error responses) which would be helpful given the tool's foundational role.

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 description coverage is 100%, so the schema already documents all 5 parameters thoroughly. The description doesn't add any parameter-specific information beyond what's in the schema, maintaining the baseline score for high schema 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 specific action ('Connect to a Bambu Lab printer'), the method ('via local MQTT over TLS'), and the resource ('printer'). It distinguishes from siblings like mqtt_disconnect by specifying connection establishment rather than termination.

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

Usage Guidelines5/5

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

Explicitly states when to use this tool ('Required before any printer control commands') and implies when not to use it (after connection is established). It distinguishes from non-MQTT siblings by specifying the prerequisite for MQTT-based printer operations.

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