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

With no annotations provided, the description carries the full burden and discloses useful behavioral traits: the URL is temporary, valid for 1 hour, and requires no authentication headers. This adds value beyond the schema, though it does not mention error handling or what happens if the job is not completed.

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 two concise sentences with the main purpose stated first, followed by key constraints. There is no redundancy or unnecessary detail, making it highly efficient.

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 adequately covers the core details: purpose, temporary nature, duration, and authentication requirements. It could be more complete by describing the response format or error scenarios, but the essentials are present.

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 already provides 100% coverage for the single parameter, job_id, with the description 'The job ID of the completed book.' The tool description does not add additional parameter semantics beyond what the schema already states, so a baseline score of 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 clearly states the specific action ('Get a temporary signed download URL') and resource ('completed eBook'). This distinguishes it from sibling tools like generate_ebook, get_job_status, list_genres, and retry_job, which have different purposes.

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 implies this tool should be used for completed eBooks, providing some context, but it does not explicitly state when to use this tool versus alternatives or mention any exclusions. No guidance on checking job status first or using retry_job if needed.

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