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

Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds non-obvious semantics the annotations cannot: that lyrics.text is your own lyrics or an auto-transcription and lyrics.yours disambiguates them. It omits any statement about analysis-not-ready/error behavior, which matters given the reanalyze_song sibling.

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?

It is short and front-loaded: the payload inventory comes first, then the workflow hint, then the lyrics-semantics note. Every sentence carries information, though the phrasing is terse enough that 'hook' and the lyrics.yours explanation read a little compressed.

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 output schema, the description has to convey the return shape, and it does so reasonably by naming the returned data families and clarifying the lyrics fields. Minor gaps remain — 'hook' and the section object are not explained, and no error/empty-analysis case is covered.

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?

Only one parameter, song_id, with 100% schema description coverage, so the schema already carries the meaning. The description adds nothing about the id's format or origin, which is the correct baseline of 3 when structured fields do the work.

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?

The description gives a specific verb+resource and enumerates the payload concretely (word-timed lyrics, tempo, beats, sections, hook), which tells an agent what this returns far better than the title alone. It never names a sibling, though, so it does not explicitly separate itself from get_song or reanalyze_song.

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?

It supplies a concrete downstream use case — 'Use the section times to choose a trim for a lyric video' — which tells the agent when this tool is the right pick in a workflow. There is no exclusion or prerequisite guidance (e.g., what to do if analysis is absent, or how it differs from get_song), so it stops short of a full when/when-not statement.

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