play_music

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

No annotations are provided, so the description carries the full burden, and it usefully discloses a non-obvious failure mode (it refuses to play a same-titled song by a different artist and reports 'could not find it'). It still omits playback side effects (queue interruption, active session requirements) and whether playback begins immediately.

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

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

Two tight sentences with the core action front-loaded and the fallback routing in the parenthetical. Nothing is padding, though the parenthetical is slightly dense and could be split for readability.

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

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

With no annotations, no output schema, and a single documented parameter, the description covers purpose, the failure behavior, and the recovery path reasonably well. Missing only playback side effects / return signaling, which keeps it short of full completeness.

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

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

One parameter with 100% schema description coverage ('Song, or "Song by Artist"'), so the schema already documents it. The description adds only an example ('Maps by Maroon 5'), which is a marginal gain over the schema, so baseline 3 applies.

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

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

Specific verb+resource: it 'searches YouTube Music and plays the best match,' with a concrete example query. It partially differentiates itself by naming search_music as the fallback when a match fails, though it does not distinguish itself from play_result or play_playlist.

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

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

Gives an explicit condition and alternative: if the song/artist match can't be found, use search_music and inspect results instead. It does not say when this tool is the wrong choice versus play_playlist or music_control, so no full exclusion guidance.

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