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

Annotations cover read-only/idempotent/non-destructive safety, but the description adds rich behavior: signed cover/preview/thumbnail URLs with dimensions and formats, 7-day signature stability for caching, and detailed meanings of analysis.lyrics.status values. This is valuable context beyond what annotations and schema provide.

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?

The description is front-loaded with a clear summary, then gives efficient field explanations. It could be split for readability, but every sentence earns its place for an output-heavy tool with no output schema.

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 explains key return fields (image URLs and lyrics status) and caching behavior. It does not cover all possible song fields or explicitly distinguish get_song_analysis, but is largely complete for the core retrieval use case.

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 description coverage is 100% and the single song_id parameter is documented in the schema itself. The description adds no info about song_id format or constraints, but baseline 3 applies when the schema already does the documentation.

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 resource and return content: 'One song and its analysis status.' However, it does not explicitly differentiate from sibling tools like get_song_analysis or list_songs, so an agent must infer which retrieval tool to use.

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?

No when-to-use guidance, prerequisites, or alternatives are given. It describes return fields but never says when to call this instead of get_song_analysis, show_songs, or similar siblings.

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