List collections

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

The annotation declares readOnlyHint: true, so the description correctly implies a read operation ('Lists collections'). It adds value beyond annotations by explaining that results vary by library_id and that collections are shared whereas playlists are private. For a read-only tool with well-scoped behavior, the description is transparent enough, though it could mention that no destructive side effects occur.

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 short, front-loaded sentences with zero waste. The first sentence states the purpose, the second clarifies scope behavior, the third contrasts with a sibling. Every sentence earns its place and no fluff.

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 lacking an output schema, the tool is simple (2 params, read-only, well-documented schema). The description covers the essential behavioral context: what collections are, scope behavior, and distinction from playlists. With high schema coverage and annotations, this is complete enough for the agent to select and invoke the tool 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 description coverage is 100% and both parameters are thoroughly documented in the schema (library_id minLength, detail enum with compact/full). The description adds no further detail about parameters beyond what the schema already provides. Baseline 3 is appropriate since schema does the heavy lifting; the description does not deepen parameter understanding.

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?

The description uses the specific verb 'lists' with the resource 'collections', and immediately clarifies that these are 'curated, ordered groups of books'. It distinguishes between collections and playlists ('Collections are shared server-wide; playlists are private per user'), which is critical given both exist as siblings. This provides clear differentiation and scope.

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?

The description explicitly states the default behavior when library_id is omitted ('returns the collections of every accessible library') and contrasts collections with playlists. However, it does not guide when to use this tool versus siblings like get_collection (to get details of a specific collection) or list_playlists, missing an opportunity for explicit alternatives.

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