Get library statistics

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

With no annotations provided, the description carries the full burden. It discloses the complete set of returned values, including a time-based component ('books added this year'), which provides meaningful behavioral context. However, it does not mention potential caveats such as units for storage or behavior for empty libraries, leaving some minor gaps.

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 ('Get library-wide totals') and then lists the specific items in a compact, easy-to-scan list. Every word earns its place, and there is no redundancy or 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 simple, zero-parameter tool with no output schema, the description is remarkably complete. It fully enumerates the data points returned, which is sufficient for an agent to understand what to expect and to decide when to use it. Additional context like return format would be nice but is not essential given the clarity.

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 tool has zero parameters, so the baseline is 4. The description adds valuable detail about what the tool returns, compensating for the lack of a parameter schema. No parameter explanation is needed because there are none.

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 has a specific verb+resource: 'Get library-wide totals' and enumerates the exact scope of metrics (books, authors, series, etc.). This clearly distinguishes it from sibling tools like get_reading_stats or get_library_statistic, which focus on different domain-specific statistics.

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 implies usage for obtaining an aggregate overview of the library, but it does not explicitly state when to choose this tool over alternatives or mention any exclusions. It lacks direct comparison with sibling tools, so the guidance is implied rather than explicit.

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