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

With no annotations, the description carries the behavioral burden itself. The verb '获取' clearly indicates a read-only retrieval, and the field list tells the agent what to expect. It does not mention behavior for invalid or missing ISBNs, but for a simple lookup tool this is a 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?

The description is one efficiently structured sentence: the action and input are front-loaded, followed by a colon and a compact list of returned fields. Every part earns its place with no redundancy.

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 tool is simple: one required parameter and no output schema. The description adequately compensates for the missing output schema by listing the returned fields, and the input requirement is clear. It is complete enough for an agent to invoke correctly, though it does not cover error cases.

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 input schema already fully describes the single ISBN parameter at 100% coverage, including the 10-or-13-digit constraint. The description only repeats 'by ISBN' and adds no additional parameter semantics beyond what the schema provides.

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 begins with a specific verb and resource: '按 ISBN 获取图书详情' (get book details by ISBN). It then enumerates the exact returned fields, making the tool's purpose unmistakable and clearly distinguishing it from siblings like search_books or list_book_tags.

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 clearly implies the tool is the right choice when the agent already has an ISBN and needs comprehensive book details. It does not explicitly mention alternatives or exclusions, but the ISBN-based scope is a clear context signal.

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