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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description adds value beyond that by telling the agent the response includes outward links for the person and their full publication list, which is useful because there is no output schema. It does not address behavior for an unknown slug, which keeps it from a 5.

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 short sentences with the identity of the tool front-loaded and the disambiguation use placed second. Some of the phrasing is promotional rather than precise ('everything in the directory they publish'), which slightly reduces informational density.

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?

For a one-parameter read tool with no output schema, the description covers what is returned and one practical use case, which is enough for an agent to call it correctly. The main gap is not-found or invalid-slug behavior, plus how a caller discovers a valid slug.

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 required parameter with full schema description coverage, so the schema already defines slug as the author's directory slug. The description adds no format, source, or resolution detail (e.g. where slugs come from, case sensitivity), so the 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 description names a specific resource (one author) and states what the caller gets back: identity/location plus everything that person publishes in the directory. It is clearly a single-record lookup rather than a listing, which implicitly separates it from list_authors, but no sibling is named, so it stops short of a 5.

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?

One concrete usage scenario is implied: use the returned feed list to decide whether two identically named people are the same person. That is a genuine disambiguation hint, but there is no explicit when-to-use versus list_authors or search, and no guidance on how to obtain the slug in the first place.

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