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

Annotations already declare readOnlyHint, idempotentHint and non-destructive behavior, so the safety profile is covered structurally. The description adds real value beyond that by explaining what comes back — a verified quote per book plus a link to the original interview/podcast/post — which tells the agent the results are citable. Missing rate-limit or pagination behavior for the limit parameter.

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?

Three sentences, front-loaded with the return contract, then when-to-use, then input formats. The example queries are long but they earn their place by matching likely user phrasing. Slight redundancy between the slug example here and in the schema.

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 two-parameter read tool with a full output schema and complete annotations, this covers everything an agent needs: what it returns, when to call it, and accepted input forms. No material gap remains.

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 description coverage is 100% and the 'person' field already documents 'name or MRB slug', so the description's 'Accepts a name or MRB slug' largely duplicates the schema. It does add concrete slug formatting via the 'naval-ravikant' example, but says nothing about the 'limit' parameter or defaults. Baseline 3 is appropriate.

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 ('Return every book a specific person has recommended') and enumerates the payload (quote, source link), which is enough to distinguish it from the inverse sibling get_book_recommenders. An agent can tell the direction of the relationship without opening either schema.

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?

The description gives concrete trigger phrasings ('what books does Naval Ravikant recommend?', 'Tim Ferriss's favorite books') and the intent class (reading habits of a public figure), which is clear context for when to call it. It never names get_book_recommenders as the inverse alternative or states an exclusion, so it stops short of a 5.

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