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

Annotations already provide readOnlyHint and openWorldHint, so the safety profile is covered. The description adds the '公开' (public) scope, implying non-public videos may not be retrievable, but it does not mention failure modes, rate limits, or any other behavioral caveats. This is acceptable but not rich.

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 a single compact sentence that conveys the core purpose immediately. There is no filler or redundant repetition of the tool name, and it is appropriately sized for a simple, single-parameter tool.

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 the rich parameter schema, read-only annotations, and presence of an output schema, the description covers the essential invocation context. It could be more explicit about edge cases such as private videos or invalid URL behavior, but it is sufficiently complete for straightforward usage.

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 coverage is 100%, and the schema itself documents supported URL formats, share_url usage from search results, and forbidden link types. The description adds no additional parameter meaning beyond restating that the input is a YouTube URL, so the baseline of 3 is appropriate.

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 states a specific action ('获取公开视频详情') on a specific resource, using a URL as the input, which clearly identifies this as a video-detail fetch. It is distinguishable from sibling tools like comments or channel info by name and phrasing, but it does not explicitly name or differentiate from those siblings.

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 offers no guidance on when to choose this tool over alternatives such as youtube_get_video_comments_by_url or youtube_search_videos. The parameter schema advises on valid URL types and what not to pass, but that addresses input formatting, not tool selection context.

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