wecom_download_media

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals key behaviors: images are uploaded to R2 and return a presigned link, other files are saved to disk, and the save_to parameter can override the default path. This provides meaningful behavioral context beyond a simple 'download', though it does not cover error handling or access permissions.

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 concise and well-structured. It starts with a clear purpose statement, then provides key behavioral details, and ends with the optional save_to parameter. Every sentence adds value without 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?

Given that an output schema exists (as noted in context signals), the description adequately covers the tool's core functionality and return behavior for different media types. It explains the two possible outcomes (R2 link or saved file) without needing to detail return values. However, it could be more complete by noting potential error conditions or limiting factors like file size.

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 has 100% coverage with descriptions for both parameters (sdkfileid and save_to). The tool description adds value by explaining the behavioral difference between images (R2 presigned link) and other files (disk save), and how save_to modifies default behavior. This provides semantic context beyond the schema's descriptions.

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 tool's core purpose: downloading media files (images, videos, voice, files) from messages. It uses a specific verb ('下载/download') and resource ('媒体文件/media files'), and it distinguishes itself from sibling tools, which focus on other operations like extracting room IDs or pulling messages.

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 does not provide any guidance on when to use this tool versus alternatives. It lacks explicit 'when to use' or 'when not to use' instructions, and no comparison to sibling tools is made. The implied usage is for downloading media from messages, but no context is given for exclusion criteria.

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