download_photo

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

With no annotations provided, the description bears the full burden of behavioral disclosure. It does this well by revealing caching behavior ('命中缓存'), local filesystem writes (download_path, image_paths), per-call logs (log_path), task_id, and error reporting. It does not mention authentication or cleanup of downloaded files, but the disclosed behavior is substantial.

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 purpose statement is front-loaded and the parameter/return sections are clearly separated. The return dictionary is somewhat verbose, but each field adds operational context (paths, task IDs, logs, durations), so the length is justified rather than bloated.

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?

Given the tool's simplicity (one required parameter) and the detailed return contract, the description is largely complete. The main gaps are the absence of explicit usage boundaries against sibling download tools and lack of authentication/storage side-effect notes, but the extensive output semantics and parameter explanation make this more than minimally viable.

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 provides only the parameter name photo_id with no description, so schema coverage is 0%. The tool description fully compensates by explicitly defining photo_id as the chapter ID and providing a concrete example ('123456'). This gives an agent everything needed to understand the sole parameter.

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 concrete action and resource: '下载本子中的特定章节' (download a specific chapter of a book). This is more specific than a mere restatement of the tool name and is distinguishable by chapter-level scope from siblings like download_album and download_cover. However, the parameter name photo_id conflicts slightly with the 'chapter ID' concept, creating minor ambiguity.

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 intended use is implied: use this when downloading a specific chapter rather than a full album or cover. But the description does not explicitly state when to prefer this tool over download_album or download_cover, nor does it mention prerequisites such as login or whether the chapter must belong to a downloaded album.

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