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

The annotations already declare this is a read-only, idempotent, closed-world query, so the safety profile needs no restating. The description adds real operational behavior beyond that: how the query is tokenized against index terms, the ranking order (all-terms pages first, bookmark-index hits above passing mentions), abbreviation resolution, and the read_as/not_indexed/not_here fallbacks. It stops short of describing result count or the effect of the limit parameter, which is the one behavioral gap.

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?

It is front-loaded with the verb and examples, and the required-parameter rule appears early. The middle section on ranking and the trailing paragraph on read_as/not_indexed/not_here are dense but each clause carries distinct behavior; the parenthetical query examples are the only mildly expendable material.

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 shoulders the burden of explaining return structure through its discussion of ranking, read_as, not_indexed (with prefix-matching terms), and not_here (with covered codes and model folders). For a search tool with a 3-param, undescribed schema this is close to sufficient; only the limit/pagination behavior and default result count are absent.

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 0%, so the description must carry the burden and largely does: 'manual' is defined as required with two valid forms (find_manuals output or model folder), and 'query' is given meaning via tokenization and the abbreviation/job-alias rules under read_as. The 'limit' parameter is never mentioned, leaving one of three params undocumented in both schema and description.

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 uses a specific verb plus resource – 'look up components, systems and jobs in one car's manual index' – and grounds it with five concrete query examples ('timing chain', 'a/t fluid', 'brake caliper'). It also separates itself from siblings by stating where 'manual' comes from (find_manuals) and by naming get_contents/read_pages as the path for non-English books.

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?

It gives clear context: use this against a manual index obtained from find_manuals, or a model folder to span all years, and it explicitly redirects non-English books to get_contents and read_pages. What is missing is an explicit exclusion boundary for near-alternatives like lookup_dtc, so an agent still has to infer when to prefer the DTC tool over this one.

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