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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds real value beyond that: a cost signal ('Costs 1 credit') and the fact that track listing and copyright are nested in `raw`. It stops short of describing pagination, error behavior, or failure modes for invalid ids.

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?

Three compact sentences, front-loaded with the resource and its fields, then the raw-data caveat, then the cost. No wasted words.

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 correctly carries the burden of describing return shape, listing top-level fields and explaining what lives in `raw`. The phantom `include_raw` parameter is the only inconsistency that leaves an agent uncertain about how to obtain the track listing.

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?

The description references `include_raw=true`, but no such parameter exists in the input schema — a mismatch that could send an agent looking for a nonexistent argument. Meanwhile `cache_max_age` (the other 50% of schema coverage) is undocumented in both schema and description, so the description does not compensate for the coverage gap.

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 enumerates the returned fields (artist, release date, genre, artwork, runtime), which is far more than a restatement of the title. It does not explicitly distinguish itself from close siblings like appleMusic_track or appleMusic_artist, though 'Album' is a reasonably distinct noun.

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?

Usage is implied rather than stated — an agent infers you call this when you have an album id or URL. The one genuine usage hint is the conditional 'behind include_raw=true' for track listings, but there is no explicit when-not or alternative routing.

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