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

Annotations already declare readOnly and openWorld, so the bar is lower, and the description still adds two things they do not: that only public track data is returned and that each call costs 1 credit. It also discloses the response fields, which matters because there is no output schema.

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 short sentences, purpose front-loaded and the field list plus the credit cost appended. Nothing is redundant or padded.

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 and no annotations covering return shape, the field enumeration and credit cost make the tool callable without opening anything else. The only real hole is the unexplained cache_max_age parameter, which is minor for a read-only lookup.

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 says nothing about parameters; the 'id' formats (numeric id, /song/ URL, album URL with ?i=) are documented only in the schema. With just 50% schema coverage, the second parameter (cache_max_age) is undocumented in both places, so the description does not compensate for the 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 verb and resource ('Track details') and enumerates the concrete fields returned (artist, album, duration, genre, release date, preview URL), which unambiguously separates it from appleMusic_album, appleMusic_artist and appleMusic_search. It stops short of naming a sibling, so it is clear but not maximally differentiated.

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 only implied: an agent can infer this is the detail lookup once a track id is known, but the description never says when to prefer it over appleMusic_search or how to obtain the id first. No exclusions or prerequisites are given.

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