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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds genuinely new behavioral context beyond them: the playback address may expire (时效性 caveat) and it enumerates the returned payload. It does not cover failure modes for an invalid/nonexistent ID, but that is a modest gap for a read-only tool.

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?

Three tightly packed clauses with zero filler: purpose first, sibling routing second, freshness caveat last. Front-loaded and free of restatement of the name.

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 one-parameter, fully documented read with an output schema and read-only annotations, the description supplies everything needed: what it returns, when to prefer the URL sibling, and the expiration caveat. Nothing an agent needs to call it correctly is missing, though it could note behavior on a stale/unknown ID.

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%: the single video_id parameter already documents the numeric-string format, an example value, and where to obtain it (search results). The description adds no syntax or format detail beyond that, 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?

States a specific verb and resource (read Haokan video detail by video ID) plus the payload it returns (播放地址, 作者摘要), and explicitly distinguishes itself from the sibling haokan_get_video_detail_by_url. An agent can route between the two ID/URL variants 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?

Gives an explicit selection rule: use this tool when you hold a video ID; use haokan_get_video_detail_by_url when you hold a page link. The alternative is named and the condition that selects it is stated, 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.