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

Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, yet the description adds a side effect the annotations cannot express: it opens the Music app when it is closed. It also enumerates the returned fields and the downstream id contract, which is real behavioral context beyond structured data.

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?

Five short sentences, each carrying distinct information: purpose, field semantics, return shape, id chaining, scope exclusion, and a side effect. Purpose and scope are front-loaded with no filler.

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?

For a 3-parameter read tool with full schema coverage and an output schema, the description covers everything an agent needs: what is searched, what is excluded, what comes back, how the id is reused, and the app-launch side effect. Nothing material is missing.

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 meaning the enum cannot: 'any' searches every text field the Music app's own search does, which tells the agent how broad the default actually is. `limit` is left to the schema, which already documents default 25 and max 100.

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?

Names a specific verb and resource ('Searches the tracks of the user's Music library') and immediately bounds the scope against a plausible confusion ('Only the library is searched, not the Apple Music catalog'). It also positions itself relative to siblings by stating the returned id is what music_play and music_add_to_playlist consume.

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 clear conditions: use it for library tracks, not catalog content, and use the returned id for playback/playlist follow-ups. It lacks an explicitly named alternative tool for the excluded catalog case, but no sibling provides that capability, so the guidance is effectively complete for the available toolset.

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