weixin_download

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

No annotations are provided, so the description carries the full burden. It adds useful context by explaining that parameters must be extracted from message items (image_item, file_item, video_item), but it does not disclose the return format, potential side effects, or error behavior. This is a moderate level of transparency.

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 sentences long, with the main purpose front-loaded and no redundant information. Every sentence contributes meaning, achieving high conciseness.

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 2-parameter tool without an output schema, the description covers the core functionality and parameter source. However, it does not mention what the download returns or where it goes, which is a notable gap for download operations. Otherwise, it is complete for the tool's complexity.

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 parameter names and examples, but the description adds important semantics by generalizing the extraction source to image_item, file_item, or video_item, beyond the schema's image-only examples. This enriches the understanding of where to find the values.

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 a specific verb ('Download') and resource ('media (image/file/video) from a received message'). It distinguishes the tool from sibling tools like weixin_send and weixin_get_config by specifying the action and source. No ambiguity about what the tool does.

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 phrase 'from a received message' provides clear context for when to use this tool, differentiating it from send-related siblings. However, it does not explicitly state exclusions or mention alternative tools, so it falls short of a 5.

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