library_stats

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

With no annotations, the description carries the full burden. It discloses the output (total books and category breakdowns) but does not specify the exact return format, data freshness, or performance implications. For a read-only summary tool, this is mostly sufficient, though additional detail on structure would boost transparency.

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, front-loaded sentence that immediately conveys the tool's function. Every part of the sentence adds value: 'Library summary' sets context, and the specifics (total books, breakdown by tags, etc.) are succinct. There is no wasted 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 no output schema, the description has the responsibility to explain the return value. While it names the components (total books, breakdowns), it omits the structure (e.g., is the breakdown a dict or list? Are counts included? Sibling tools like get_book_metadata have more detailed output descriptions. The description is complete enough for a simple summary but lacks specificity.

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?

There are zero parameters, so the schema coverage is trivially 100%. Per instructions, the baseline for 0 parameters is 4. The description adds no parameter information, but none is needed. The tool works without input, so the description is adequate.

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 that the tool returns a library summary including total book count and breakdowns by tags, authors, series, and formats. This is a specific verb (summarize) and resource (library stats). It distinguishes itself from sibling tools like get_book_metadata (specific book) and search_books (list) by focusing on aggregate 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 tool's purpose implies it should be used when overall library statistics are needed. However, there is no explicit guidance on when to use this vs. alternatives like list_categories or search_books, nor are there any prerequisites or exclusions mentioned. The brevity leaves the agent to infer usage context.

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