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

Annotations already mark the tool as readOnly and openWorld, so the description's main contribution is the explicit constraint that only numeric object_id is accepted, plus the schema's note to avoid encrypted_object_id or video links. This adds practical behavioral context beyond the annotations. However, it does not disclose potential error conditions or response nuances, but given the annotations cover safety, this is acceptable.

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 extremely concise – two short sentences. It front-loads the primary purpose and then states the key constraint. There is no redundancy or filler. Every word contributes to understanding the tool's core function and limitation.

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 single-parameter tool with an output schema, the description covers the essential purpose and the one critical input restriction. It does not explicitly describe the return format, but the presence of an output schema mitigates that gap. Given the tool's simplicity, the description is reasonably complete, though it could mention whether the share link is a full URL or relative path.

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 documents the parameter with an example and a caution against passing encrypted IDs or links, giving 100% coverage. The description adds the additional constraint that the object_id must be numeric, which is not present in the schema description. This extra clarity nudges the score above the baseline of 3, though the addition is minor.

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 action ('获取分享链接' – get share link) and the resource ('微信视频号作品 object_id' – WeChat Channels work object_id), making the purpose specific. It does not explicitly differentiate from sibling tools like wechat_get_video_detail_by_object_id or wechat_get_video_comments_by_object_id, but the verb 'get share link' is unambiguous enough that an agent can infer its distinct role.

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 gives no guidance on when to use this tool versus alternatives such as wechat_get_video_detail_by_url or wechat_get_video_comments_by_object_id. It only states a constraint ('只接受数值 object_id') but does not explain scenarios or trade-offs. An agent must rely on the tool name and schema alone to decide, which is insufficient for a family of similar video tools.

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