Bambu Lab MCP Server

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sign_message

Sign messages with X.509 certificates to authenticate communication with Bambu Lab 3D printers, enabling secure printer control and bypassing firmware authentication restrictions.

Instructions

Sign a message with X.509 certificate for authenticated printer communication. Uses the extracted Bambu Connect certificate to bypass firmware auth restrictions.

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": {
      "device_id": "<device_id>",
      "message": "<message>"
    },
    "name": "sign_message"
  }
}

Input Schema

Name	Required	Description	Default
`device_id`	Yes	Printer device ID
`message`	Yes	Message payload to sign

Schema Changelog

Changes observed during successful MCP inspections.

First observedv3.0.0Feb 6, 2026

TDQS

A3.7/5.0

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 tool uses an extracted Bambu Connect certificate and bypasses firmware authentication, which are important behavioral traits. However, it doesn't mention security implications, error conditions, or what happens to the signed output.

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 functionality, and the second adds crucial implementation 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.

Completeness3/5

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

For a cryptographic signing tool with no annotations and no output schema, the description provides adequate purpose and context but lacks details about the signing algorithm, output format, security considerations, or error handling that would be important for safe usage.

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 both parameters. The description adds context about the certificate source and authentication bypass, but doesn't provide additional parameter-specific semantics beyond what the schema provides.

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 ('Sign a message'), the resource ('with X.509 certificate'), and the purpose ('for authenticated printer communication'). It distinguishes this tool from all sibling tools which involve printer control, camera operations, or file management rather than cryptographic signing.

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

Usage Guidelines3/5

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

The description implies usage context ('bypass firmware auth restrictions') but doesn't explicitly state when to use this tool versus alternatives. No sibling tools appear to offer similar signing functionality, so there's no direct alternative guidance provided.

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