Download book

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

Annotations already declare this is a non-read-only, non-idempotent, open-world operation, so the safety profile is covered. The description adds genuinely new behavior: the file is saved to ANNAS_DOWNLOAD_PATH, it is verified, and the call returns path plus bytes. It omits failure/retry behavior, though timeout handling is documented in the schema.

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 short sentences, no filler, with the core action and its precondition front-loaded and the format caveat last. Every sentence carries information an agent needs before invoking the tool.

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?

With an output schema covering the returned path and byte count and annotations covering the safety profile, the description is close to complete: it explains the save location, verification, and non-converting format. It could note permission or rate-limit expectations for an open-world download, but nothing essential to correct invocation 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%, so each of the four parameters is already documented with format, range, and defaults. The description reinforces that format sets only the extension and that hash comes from search, but that meaning is largely duplicated from the schema rather than extended, so the baseline 3 applies.

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?

Names a specific verb and resource (download a book) and ties the input to its source ('hash from search'), which cleanly separates it from book_search and from the sibling article_download. It stops short of explicitly contrasting itself with article_download, but the 'book' framing makes the distinction inferable.

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?

States the precondition that the hash must come from a prior search, which routes the agent through book_search first, and adds the caveat that format only sets the extension rather than converting. It does not spell out when to prefer this over other download paths or exclusions, so it is clear context without full alternative coverage.

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