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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the description's job is to add ordering and scope – which it does with 'newest first' and the two narrowing modes. Defaults and pagination limits are only in the schema, which is an acceptable but minor gap.

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 tight elements: capability, use case, example – front-loaded and waste-free. The example string is slightly redundant with a fully documented schema, but it usefully illustrates combining book_id and search.

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 an output schema present, return values needn't be enumerated; the description nonetheless previews page, speaker, notes and themes, which helps the agent decide whether the result answers the user's question. What remains unstated – default limit behavior, whether search is full-text or substring – is minor for a simple read tool.

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 100%, so the baseline is 3; the description adds value by explaining that narrowing can be to one book OR to quotes containing given words, and by supplying a combined example with two parameters. That gives an agent a sense of how filters compose beyond the per-field schema text.

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 ('lists the quotes and passages the reader has saved'), plus ordering ('newest first') and returned fields. It is clear what the tool returns, but it never names or contrasts the closest sibling (list_quotes_due_for_review), leaving that distinction to be inferred.

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?

'Use when the user asks for their saved quotes or highlights, or for what they saved from a particular book' gives a concrete trigger and scope. It stops short of stating exclusions (e.g., that review-queue quotes belong to list_quotes_due_for_review), so it is clear guidance without full routing.

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