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

Goes well beyond the readOnly/non-destructive annotations: it discloses the ordering rule per mode (time desc vs. keyword hit-count ranking), the no-filter default of the 20 newest site-wide posts, Beijing-time day semantics for since/until with until inclusive, and the warning not to assume results are fresh because each item carries its real publish time. It also tells the agent to report honestly when the window is empty — real behavioral guidance an agent could not infer from structured fields.

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 purpose, then cleanly enumerated ① time-only / ② keyword / ③ neither, followed by parameter notes. Some of the trailing time-parameter explanation duplicates the schema text and could be trimmed without loss.

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?

With an output schema present, the description need not explain return shape, and it still covers the remaining ambiguities an agent would hit: default result count, sort order per mode, timezone interpretation, inclusivity of until, and empty-result handling. Nothing needed for a correct call 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 timezone/until-inclusive/since_hours-precedence details largely restate the schema. What the description genuinely adds is mode-level parameter semantics: which parameters to combine for a chronological feed vs. relevance ranking, and that keyword matches post body and ranks by hit count within the window — meaning absent from the schema.

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 (检索公开帖子) plus the three operating modes, so an agent can immediately tell it apart from siblings like get_post_detail, get_post_replies, or my_posts which operate on a single post or a user's own posts.

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 concrete user-question triggers for the time-only mode (「最近有什么新帖」「今天社区在聊什么」「10 月 25 日那天发了什么」) and defines what happens when keyword is supplied or nothing is supplied. It stops short of naming sibling alternatives (e.g. 'for a specific user's posts use my_posts'), so routing is implied rather than explicit.

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