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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, and the description goes well beyond them: data provenance (AcousticBrainz recording analyses), agreement count across analyses, BPM only when analyses agree, estimated vocal range, returned links, and explicit not-found behavior. That is rich behavioral context for a lookup tool.

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?

Four sentences, front-loaded with purpose, then usage, then parameter guidance, then failure behavior. No redundant restatement of the title or annotations; every sentence carries information.

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?

Despite an output schema existing, the description still explains the meaningful return elements (relative key, agreement count, BPM, range, links) and the not-found fallback. Combined with the fully described schema and safe-read annotations, an agent has what it needs to call this correctly.

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?

Schema coverage is 100%, so the baseline is 3, but the description adds intent-level meaning: semitones is framed as 'if they want it higher or lower' for voice suitability, and title lookup is framed as identifying a song rather than a free-text query. The artist parameter is left to the schema, which already explains its disambiguation role.

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?

States a specific verb and resource (look up key, tempo and vocal range of a song by title) plus the backing source (AcousticBrainz analyses in Tera Studio's list). However, it does not acknowledge the sibling find_song_key_and_tempo, which also returns tempo, or shift_song_key, which also covers transposition — so the boundary between this tool and its siblings stays blurry.

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 a clear triggering context ('when someone names a song and asks its key or tempo, or whether it suits their voice') and a secondary case for the semitones parameter. It stops short of saying when NOT to use it or naming the overlapping alternatives (find_song_key_and_tempo, shift_song_key).

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