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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds valuable context beyond annotations: the data source (standardebooks.org OPDS 2.0 JSON feed) and 'no auth required', plus the concrete set of download link formats. This gives an agent confidence about external dependencies and expectations without contradicting the annotations.

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 dense sentences, front-loaded with the primary action and scope, followed by return fields and data source. Every sentence contributes substantive information; no filler or repetition of schema details that are already present.

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?

The combination of a rich schema (all params documented), output schema presence, and description covering return fields, sort options, and auth requirements makes this fully complete for an agent to invoke correctly. No critical information is missing.

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 schema already richly documents query, sort, page, and per_page with defaults and examples. The description adds only minimal extra meaning (e.g., sort names, query example in schema is actually richer). Since the schema carries the heavy lifting, a 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?

The description states a specific verb and resource ('Search the Standard Ebooks catalog'), specifies the search dimensions (title, author, subject keyword), and details the return fields and sorting options. It clearly differentiates this from books.* siblings (e.g., Standard Ebooks new_releases, gutendex, librivox) by naming the catalog and data source.

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 clear context for when to use it: when searching the Standard Ebooks catalog by title, author, or subject. It does not explicitly mention alternatives such as standard-ebooks.books.new_releases, but the search-focused framing makes the use case obvious. No exclusions are stated, but none are necessary for a read-only search tool.

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