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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description then adds genuinely useful behavioral detail the annotations cannot: death_year is null if unknown or modern, death_text is a display string, and the book list includes co-authored works with a downloaded flag. With no output schema present, this return-shape disclosure carries real weight.

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 the purpose, then returns, then the parameter hint and example — a sensible order with no wasted discussion. Minor redundancy: the Arabic line 'جلب بيانات مؤلف' merely restates the English opening sentence, and the example sentence is somewhat elaborate.

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?

Because no output schema exists, the description does the work of enumerating the return payload (author_name, death_year, death_text, per-book fields), which is exactly what an agent needs to consume the result. The only real gap is that it never tells the agent how to find a valid author_id, which matters for a tool whose sole required input is an opaque id.

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 coverage is 100%, so the baseline is 3, but the description goes beyond the schema by explaining the purpose of include_books (skip the book list when only name/death year is needed) and by giving a concrete call example (author_id:57). It adds a modicum of meaning over the structured fields, though response_format's elaborate schema text needs no help.

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 ('Fetch metadata for an author by author_id') and enumerates what is returned, so the agent knows exactly what this tool produces. However, it never differentiates itself from the many sibling lookup tools (e.g. shamela_search_authors as the way to obtain an author_id), so sibling disambiguation is left implicit.

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?

There is usable guidance for one parameter ('Use include_books=false to skip the book list when you only need name/death year'), but nothing about when to choose this tool over alternatives such as shamela_search_authors or how a candidate author_id is discovered in the first place. Usage is implied by the description rather than stated.

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