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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds value by explaining that the search is full-text across specific metadata fields and warns that large 'fields' values can cause huge responses, which is a practical behavioral trait. It also states the return type.

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?

The description is concise, spanning three sentences without redundancy. It front-loads the main action and includes a useful performance tip and return note. Minor punctuation issue (double period) does not detract from overall clarity.

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 read-only search tool with a fully documented schema and clear annotations, the description covers the necessary aspects: operation, search scope, performance guidance, and return format. No output schema exists, but the 'Returns' line sufficiently outlines the result type.

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?

The schema provides 100% coverage for all parameters (q, limit, fields), each with clear descriptions. The description's guidance to keep 'fields' small mirrors the schema's own note about compact responses, adding no new semantics beyond what is already structured.

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 clearly states the tool searches books by keyword and specifies the search scope (titles, authors, subjects). It is specific and actionable, though it does not explicitly differentiate from the sibling tool search_authors beyond naming 'books'.

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 usage is implied: this is the tool for keyword search in books. It offers no explicit alternatives or exclusions, and does not mention search_authors as a complementary or alternative tool. The performance tip about 'fields' is useful but not about tool selection.

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