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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered elsewhere. The description adds only the shape of the returned data (biography, dates, page address, books), which is genuine but modest value. It says nothing about behavior on a missing author or which author representation is returned.

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?

One short sentence-fragment with no filler, so it is maximally concise. However, terseness here shades into under-specification: the fragment omits a verb and the input form, so brevity costs clarity rather than serving it.

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?

This is a simple one-parameter read tool with full schema coverage and complete safety annotations, and there is no output schema — so the description's enumeration of returned fields usefully compensates for that absence. The main remaining gap is error/not-found behavior, which is minor for this complexity.

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?

There is a single parameter with 100% schema description coverage ('The author's id or slug'), so the schema carries the semantics. The description never mentions the input at all — it does not confirm that either an id or a slug is acceptable, though the schema does. Baseline 3 applies.

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 fragment names the resource (author) and enumerates what comes back (biography, life dates, page address, books), so the general intent is inferable. But it uses no verb — no 'retrieve' or 'fetch' — and gives no hint of the lookup key, so an agent must infer from the tool name alone. It also does nothing to distinguish this from the sibling search_authors.

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 no usage guidance at all: no statement of when to call this instead of search_authors, and no mention that the input is an id or slug (which is what actually separates the two). The agent must deduce the distinction from the tool name and schema.

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