Get library stats

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

Annotations already provide 'readOnlyHint: true', so the safety profile is covered. The description adds useful behavioral context by listing the specific statistics returned, which goes beyond the annotation. No contradictions are present.

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 a single, well-structured sentence that front-loads the purpose ('Statistics for one library') followed by a specific list of included statistics. Every element contributes value with no redundant text.

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?

Given the tool has one parameter, no output schema, and readOnly annotation, the description provides sufficient information about the returned data. Minor gaps exist (e.g., no mention of error handling or limits), but it is complete enough for typical use.

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% for the single 'library_id' parameter, which includes a clear description ('Library id, as returned by list_libraries'). The tool description does not add additional meaning or usage hints beyond the schema, so a baseline score of 3 is appropriate.

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 clearly states the verb ('get') and resource ('library stats'), and specifies the exact statistics included: number of items, authors, genres, total duration, size, longest and largest items. This distinguishes it from siblings like 'get_library' (which likely returns metadata) and other stat tools.

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 provides no guidance on when to use this tool versus siblings such as 'get_listening_stats', 'get_year_stats', or 'get_library'. No exclusions or alternatives are mentioned, leaving a gap for an AI agent deciding between similar stat endpoints.

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