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

Annotations already cover read-only, idempotent, closed-world, non-destructive, so the bar is lower; the description still adds substance by disclosing the eligibility constraint (active listing required) and interpreting human_verified as Telegram-linked sign-in vs. email-only accounts. It also warns the board performs no identity verification, which is genuinely non-obvious behavioral context.

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?

Purpose and identifier mapping are front-loaded, and every sentence carries information. It is on the dense side — the parenthetical field enumeration and the identity-verification disclaimer could be tightened — but nothing is 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?

With no output schema, the description correctly shouldered the burden of naming the returned fields and explaining human_verified, and it adds the eligibility rule and a pointer to about_these_numbers. What remains thin is failure behavior for an author without an active listing, which is only implied.

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 only 50%, and the schema's author_id entry is a bare integer with no description; the text compensates by defining it as listing.author.id, which is exactly the missing semantic. It also points to about_these_numbers for field meaning, though the language parameter is left to the schema.

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?

Opens with a specific framing ('Who is behind a listing') and immediately anchors the key parameter (author_id = listing.author.id), then enumerates what the profile returns. An agent can tell this is an author-profile lookup distinct from get_listing/search_listings, though the siblings are never named explicitly.

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 exclusion ('Only authors with an active listing have a page'), which tells the agent when this call will fail or be pointless. The author_id = listing.author.id note implies the chaining pattern from a listing, but no alternative tool is named for the case where no listing exists.

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