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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the description need not repeat safety. It adds that page_token pagination is supported, which is partially redundant with the schema but frames the behavior. No contradictions with annotations.

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?

Two short sentences, front-loaded with the core action and immediately followed by routing and pagination guidance. Zero filler; every clause contributes information.

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?

Combined with a 100%-documented schema, read-only annotations, and an output schema, the description covers the core action, the routing rule, and pagination. Nothing essential is missing for an agent to decide to call and exercise the tool correctly.

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%, and the schema already explains keyword's negative constraints ('不要传主页链接、用户 ID 或 page_token') and page_token's lifecycle ('原样传入同一关键词...不可跨能力使用'). The description only broadly mentions keyword search and pagination, adding no semantics beyond the schema. 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 '按关键词搜索 Bilibili 用户' (search Bilibili users by keyword) – a specific verb, resource, and method. It differentiates from user-profile sibling tools by noting that if a user_id or profile URL is already available, the corresponding profile tool should be used. The mention of pagination further clarifies the tool's scope.

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?

Provides explicit routing: '已有 user_id 或用户主页链接时使用对应用户资料工具' (if you already have a user_id or profile URL, use the corresponding profile tool) – a clear when-not condition. It does not name exact sibling tools (e.g., by_user_id vs by_profile_url) nor contrast with other search tools (videos/articles), leaving a small inference gap. Overall it clearly frames search versus direct lookup.

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