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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is fully covered. The description adds that results are snippets (passages) rather than full books and describes the returned fields, which is useful, but doesn't discuss ranking, matching mode, or corpus size.

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?

Three tight sentences, front-loaded with the core action and result format. The phrase 'This is the headline feature' is slightly promotional but still informative about prominence. No wasted words overall.

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 3-param read-only search with full schema coverage and no output schema, the description covers purpose, scope, result shape, and the one optional filter. It stops short of explaining matching behaviour or ranking, which would have made it fully self-sufficient, but nothing critical is missing.

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 query, limit (with default/max), and gutenberg_id. The description repeats the gutenberg_id restriction without adding syntax or semantics beyond the schema, matching the baseline for fully documented params.

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 (search), scope (inside indexed public-domain corpus), and resource (books), plus the return shape (matching passages with title, author, snippet). Distinguishes itself from siblings like book_search (metadata) and book_get_text (full text of one book) by emphasizing in-text phrase search.

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?

Explains that it finds where a passage appears across great books and that gutenberg_id optionally restricts to one book. It doesn't explicitly name book_search or book_get_text as alternatives, but the search-vs-fetch distinction is clear enough to route the agent.

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