musescore-mcp

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change_tempo

Modify the tempo in a MuseScore file by setting the BPM and beat unit. Replaces all existing tempo markings with the new value.

Instructions

Change the tempo by modifying MusicXML and elements.

Replaces all existing tempo markings in the score.

Args: score_b64: Base64-encoded score file. input_suffix: Input extension, e.g. "mscz". bpm: New tempo in beats per minute (1–400). beat_unit: Beat unit for the metronome marking: quarter, half, eighth, whole.

Returns: Modified MusicXML as a UTF-8 string.

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": {
      "score_b64": "<score_b64>",
      "input_suffix": "<input_suffix>",
      "bpm": "<bpm>"
    },
    "name": "change_tempo"
  }
}

Input Schema

Name	Required	Default
`score_b64`	Yes
`input_suffix`	Yes
`bpm`	Yes
`beat_unit`	No	quarter

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0May 10, 2026

TDQS

B3.4/5.0

Behavior4/5

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

The description discloses that it replaces all existing tempo markings (destructive behavior) and returns modified MusicXML as a string. With no annotations provided, this is reasonably transparent, though missing details on side effects and error handling.

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 concise, with a clear first sentence stating the core action, followed by a structured Args list and return type. No extraneous information.

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?

The description covers the tool's action and return value adequately for its simplicity, but lacks usage guidelines and error scenarios. With an output schema present, return details are partially covered.

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?

The 'Args' section repeats parameter names but adds constraints: bpm range (1–400) and beat_unit options. However, it does not elaborate on score_b64 format or input_suffix beyond their names, leaving room for ambiguity.

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

Purpose4/5

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

The description clearly states it changes tempo by modifying specific MusicXML elements and replaces all existing tempo markings. This distinguishes it from sibling tools like change_time_signature, but does not explicitly mention sibling differentiation.

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 is provided on when to use this tool versus alternatives like change_time_signature or other tempo-related operations. The prerequisites and context of use are not addressed.

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