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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful return-shape context (video play info, video description is not a transcription) but says nothing about pagination, errors, or rate limits. Reasonable value-add given annotations carry the safety burden.

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?

Front-loaded with the primary capability and tightly scoped to three short clauses with no filler. The semicolon-chained clauses are slightly dense but every statement earns its place.

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 values need not be explained, and annotations cover the read-only/open-world profile. Purpose, ID source, and the by_url alternative are all present; the only gap is behavioral detail on large-result handling, which is minor for a single-ID lookup.

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?

Only one parameter and schema description coverage is 100%; the schema already documents post_id, its numeric pattern, and the warning not to pass a link. The description's '输入内容数字 ID，可接续搜索结果' restates the same information rather than adding syntax or format detail, so 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+resource (读取头条文章、视频或微头条详情) and enumerates the returned content (正文、图片、作者、互动数据、视频播放信息), so the agent knows exactly what this retrieves. It also explicitly names the sibling it is not (toutiao_get_post_detail_by_url), letting an agent 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?

Gives a clear selection rule: use this tool when you have a numeric content ID, which can be carried over from search results, and use toutiao_get_post_detail_by_url when you have a link instead. No explicit exclusions beyond that, but the alternative routing is unambiguous.

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