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

Annotations already declare readOnly, idempotent, non-destructive and open-world behavior, so safety is covered. The description adds value beyond that by disclosing the return payload shape and the downstream contract that lang+slug are prerequisites for other tools. It stops short of describing matching semantics (exact vs fuzzy, ordering, what happens when a language has no matches), so not a 5.

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?

Front-loaded with purpose, then when-to-use, exclusion, and return shape — a sensible ordering with almost no filler. Minor deduction for the trailing return spec, which is malformed/truncated ('books[']') and uses nested braces that are harder to parse than a plain list.

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?

With no output schema, the description correctly compensates by naming the returned fields and envelope keys. Combined with the routing guidance and annotation coverage of the safety profile, an agent can call this correctly; only the garbled return-key syntax and unstated pagination/limit behavior keep it from being fully complete.

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%, so query, lang and limit are already documented in the schema, giving a baseline of 3. The description reinforces that lang scopes the search to a single language and that its output feeds other tools, but adds no new format, default or edge-case detail for the parameters themselves.

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?

States a specific verb and resource ('search the catalog by title or author') plus the scoping constraint ('within one language') and enumerates the returned record fields. It is clearly distinguishable from cyberlibrary_fulltext_search and the semantic/passage search siblings because the match target (title/author) is explicit.

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?

Contains an explicit 'When to use' clause tied to a concrete agent need ('you have a title or author and need the lang+slug that every other tool requires') and an explicit 'Do not use' exclusion naming the correct alternative. This is exactly the routing information an agent needs to choose between overlapping search tools.

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