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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds substantive behavior beyond that: no pagination support and no guarantee the target account appears in results – both real usage constraints. It stops short of discussing rate limits or result-count bounds, so not a full 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 action, then constraints, then routing to alternatives – a logical order with essentially no filler. The return-field enumeration is somewhat long but arguably useful; slight verbosity keeps it from a 5.

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-parameter suggestion tool with an output schema, the description covers purpose, constraints (no pagination, non-deterministic inclusion), and sibling routing. Nothing an agent needs to invoke it correctly is absent.

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 already explains that keyword is a name/term and must not be an ID, link, or pagination token. The description adds no syntax or format detail beyond the schema, so the 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 and resource ('获取微博搜索框按关键词联想的少量用户候选' – typeahead user suggestions by keyword) and explicitly differentiates from the user-search and user-detail siblings. The scope qualifier ('少量用户候选') precisely frames it as an autocomplete-style tool rather than a full search.

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 both alternatives and the exact condition that selects each: use user search when pagination is needed, use user detail when a user_id or profile link already exists. This is explicit when-to-use/when-not guidance, not inference.

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