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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world). The description adds genuine value beyond them: the screen_checked=false caveat explains a conditional failure mode where film/TV status is unknown, and 'Misspellings are fine' signals input robustness.

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?

Purpose and examples are front-loaded and the screen_checked caveat is placed last, which is good ordering. However, the opening 'Books Like This. A book's details and any film or series made from it.' restates the title verbatim, which is redundant padding.

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?

There is no output schema, so the description carries the return-value burden, and it does explain that the tool returns book details plus adaptation status, including the unknown-status edge case. For a simple single-item lookup this is nearly complete, though the exact response shape is not described.

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 the schema already documents all three parameters with constraints and enum-like values for country. The description only adds the misspelling-tolerance note for title, which is marginal beyond what the schema provides – baseline 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 states a specific verb and resource – retrieving a book's details plus any film/series adaptation – which is distinguishable from the sibling tools find_similar_books and get_author_books. It does not explicitly name those siblings, but the single-book framing makes the scope clear.

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?

Concrete trigger phrases ('tell me about Project Hail Mary', 'is The Name of the Wind being made into a film?', 'how long is Dune?') give clear usage context, including the adaptation-check angle. It stops short of contrasting with alternatives like find_similar_books or get_author_books, so no exclusions are stated.

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