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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and network behavior are covered structurally. The description adds a genuinely useful operational caveat that annotations do not convey — the playback URL may expire ('播放地址可能过期'). It stops short of describing pagination or freshness of the author summary, but the expiry warning is real added value.

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?

A single compact sentence front-loads the purpose, then the alternative route, then the expiry caveat. Every clause earns its place with no 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?

An output schema exists, so return-value documentation is not the description's burden. With purpose, sibling routing, the expiry warning, and full schema coverage of the sole parameter, an agent has everything needed to invoke this correctly.

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% for the single url parameter, and the schema itself spells out the required format (https://haokan.baidu.com/v?vid=数字ID, obtainable from search results' share_url). The description only restates that input comes from a page link, adding no syntax or format detail beyond the schema, 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 ('读取好看视频详情、播放地址和作者摘要' — read Haokan video detail, playback URL, author summary), which is more specific than the title/name alone. It also explicitly distinguishes itself from the sibling haokan_get_video_detail_by_video_id, so an agent can route between the two without opening either schema.

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 routing condition explicitly: use this tool when you have a page link, and use haokan_get_video_detail_by_video_id when you only have a video ID. That is a clear when/when-not with a named alternative, leaving nothing to inference.

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