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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower, and the description still adds substantial behavior: a 10-result cap, ranking by term frequency, the unscoped nature of the search, and the meaning of the '[footnote match]' and '[token match]' result qualifiers. These are result-interpretation behaviors an agent cannot infer from annotations or schema.

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 and return shape, then constraints, then the qualifier legend, then sibling routing. Every sentence carries distinct information (scope, return limit, tool chaining, language, result qualifiers, ranking, alternative) with no filler.

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?

Even though an output schema exists, the description adds the fields an agent needs to act on results, including the id used for fetch, the result cap, and the qualifier legend. Combined with the sibling routing and language requirement, nothing essential to correct invocation 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% and the single parameter is already documented as 'Arabic search text — a quoted wording or a topic.' The description's 'Query in ARABIC' and 'a quoted wording or a topic' largely restate the schema, so per the high-coverage baseline a 3 is correct.

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'), the exact resource scope ('all 8,594 works of the classical Islamic library'), and the return contract (up to 10 pages as {id, title, url}). It also explicitly contrasts itself with the sibling search_library ('unscoped... ranks by term frequency'). An agent can distinguish it from search_library and fetch without opening any schema.

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?

Gives explicit when-to-use routing: 'for a hadith, tafsir or fiqh question, search_library with a scope ranks the standard sources first,' naming the alternative and the condition that selects it. It also chains usage to the fetch tool ('Pass an id to `fetch` to read that page') and imposes a hard input constraint ('Query in ARABIC').

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