reaper-mcp

by vecnode

Overview Schema Source Related Servers Discussions Admin

Rust

Local

transport_set_tempo

Set the project tempo in beats per minute to define playback speed. Adjusts the tempo of the entire REAPER project.

Instructions

Set the project tempo in beats per minute.

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": {
      "bpm": "<bpm>"
    },
    "name": "transport_set_tempo"
  }
}

Input Schema

Name	Required	Description	Default
`bpm`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jul 10, 2026

TDQS

C2.8/5.0

Behavior1/5

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

No annotations are provided, and the description omits behavioral details like valid BPM range, effect on playback, or whether existing tempo is overwritten. The agent has no information about side effects or constraints.

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, no redundant information. However, brevity comes at the cost of completeness, lacking important details.

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 has only one parameter but no output schema or annotations, the description is too minimal. It does not explain what happens after setting tempo, valid input constraints, or dependency on project state.

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

Parameters2/5

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

With 0% schema description coverage, the description should compensate but only clarifies the unit (beats per minute). It does not specify whether the value must be an integer or float, range limits, or typical values.

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 specifies the verb 'Set', the resource 'project tempo', and the unit 'beats per minute'. It is distinct from sibling tools which focus on playback control, track management, or other functions.

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 given on when to use this tool, such as whether the transport should be stopped or if tempo can be changed during playback. No alternatives are mentioned, though no other sibling tool sets tempo.

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