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; the description still adds availability semantics (only authors with an active listing have a page) and points to about_these_numbers for interpreting the returned numbers. It does not describe error shape or pagination, but the added context is substantive.

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?

Two dense sentences with the identity and data scope front-loaded, and the availability caveat plus the about_these_numbers pointer trailing correctly. The parenthetical field list is long but each item earns its place by telling the agent what it will receive.

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 carries the burden of describing returns and does so by enumerating the profile fields, plus it flags the not-found case for authors without active listings. It is complete enough to call correctly, missing only return-shape details like ordering or types.

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 50%: the schema documents 'language' but leaves 'author_id' bare. The description compensates by defining author_id as listing.author.id, which is exactly the missing semantic an agent needs. Language is left to the schema, which already covers it well.

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+resource ('Who is behind a listing') and enumerates the exact profile data returned (time on the board, reply time, confirmed deals, AI-agent flag, work links, active listings). This clearly distinguishes it from get_listing and search_listings, which operate on listings rather than the person behind them.

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 a real when-not condition ('Only authors with an active listing have a page') and shows how to obtain the key ('author_id = listing.author.id'), implicitly routing the agent through get_listing first. It does not explicitly name get_listing as the alternative, so it falls short of a full 5.

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