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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful behavior beyond that: auth-dependency (登录时附带 viewerHasLiked / isMine), the fact that the content is mostly official-generated rather than user dynamics, and that the comment section is globally empty. Error/not-found behavior is still unstated, so not a 5.

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 core verb+resource and return fields, then a bracketed 口径 note carrying the domain caveats. Dense but every clause earns its place; slightly more verbose than strictly necessary.

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-param read tool with 100% schema coverage and no output schema, the description supplies the return-field list, the auth-dependent fields, and the cross-domain boundary. Nothing an agent needs in order to call it correctly is missing.

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%, so the baseline is 3. The description adds real meaning beyond the schema: id is a content-stream id, not a moment id, and the two id spaces are not interchangeable — exactly the interoperability warning an agent needs before passing an id from another tool.

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 ('按 id 查内容流里的单条') and enumerates what is returned (正文 / 图片视频 / 挂卡 attach / 作者). It also explicitly contrasts itself with the sibling content type: 用户动态与评论在消息圈（get_moment / comment_moment）. An agent can distinguish it from get_moment 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?

Names the alternatives (get_moment / comment_moment) and gives the discriminating condition that 两者 id 不通用, plus a when-not cue (don't point users to the comment section). Clear routing context, though it doesn't address list_posts vs get_post selection explicitly.

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