modularsynth-mcp

Overview Schema Source Related Servers Discussions Admin

Play song

play_song

Starts playback of a modular synth song from its first line or a specified zero-based line, letting each scene play for its bars and restarting clocks on the first beat.

Instructions

Play the song from its first line (or from line "from", counted from 0): the scene of each line plays for its bars, clocks restart on the first beat. Stop it with set_transport running: false.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "play_song"
  }
}

Input Schema

Name	Required	Description	Default
`from`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.3.1Nov 2, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations mark it as non-read-only and non-destructive, and the description adds real behavioral context: scenes play for their bars and clocks restart on the first beat, which is a meaningful state side effect. It still doesn't say whether playback is asynchronous or whether an in-progress transport is interrupted.

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?

One dense sentence with the default behavior front-loaded and the escape hatch appended; nothing is redundant. The nested quoting around "from" makes it marginally harder to parse than necessary.

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 one-parameter, no-output-schema tool this covers the essentials: what plays, from where, and how to stop. Only the return/blocking behavior and interaction with an already-running transport are unstated.

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

Parameters4/5

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

Schema coverage is 0% for the single `from` parameter, so the description carries the load — it explains that it is a line index counted from 0 and that omitting it starts at the first line. Bounds/max behavior is only in the schema, hence not a 5.

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?

States a specific verb (Play) and resource (the song, i.e. its lines/scenes), and distinguishes the behavior from sibling play_notes by explaining that each line's scene plays for its bars. The starting-point semantics make it immediately distinguishable from transport or note tools.

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

Usage Guidelines4/5

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

Explicitly routes the stop case: "Stop it with set_transport running: false" names the sibling and the parameter value needed. It doesn't state when to prefer play_notes or how this interacts with a paused transport, so it stops short of full 5 guidance.

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