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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description doesn't need to re-state that. It adds valuable context: that it returns shelf, rating, and progress, and that it avoids pulling the entire library. This goes beyond annotations by describing the result content.

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 sentences, front-loaded with the core answer, and efficiently conveys the purpose and the key benefit (avoiding full library pull). No wasted words.

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 simple tool with one parameter and no output schema, the description covers the main purpose and result. However, the lack of parameter documentation and unspecified response structure (e.g., what happens when the book is not on any shelf) leaves some gaps. But given the simplicity and annotations covering safety, it's adequate.

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 one required parameter, workId, but the schema has no description (coverage 0%). The description does not explain what workId is or how it should be formatted; it only refers to 'this book' without connecting it to the parameter. The tool name and context imply it's an identifier, but the description provides no explicit guidance, leaving the agent to guess.

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 what the tool does: checks whether the signed-in reader has a specific book, and returns shelf, rating, and progress. It distinguishes from siblings like get_my_library (which lists all books) and get_book (which is not reader-specific), and the phrase 'Answers "have I read this?"' captures its unique purpose.

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?

It provides a clear use case: checking a single book's status without pulling the whole library. This implies when to use it (for a specific book) and implies not for bulk operations, though it doesn't explicitly name alternatives or exclusions.

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