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

Annotations already establish readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds a meaningful data-fidelity caveat (缩略统计为近似值) that annotations cannot express, though it says nothing about rate limits, auth, or response shape.

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?

A single semicolon-joined sentence packs purpose, a caveat, and the routing rule, with the core action front-loaded and zero redundant phrasing.

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 only one parameter at full schema coverage, an output schema present, and annotations covering the safety profile, the description supplies everything else an agent needs: what it returns in general terms, the accuracy caveat, and the sibling routing.

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%: the schema already states the numeric-ID pattern and warns against content IDs, links, or profile handles. The description adds no parameter detail beyond that, 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+resource (读取头条用户资料和主页统计) and immediately disambiguates against the sibling toutiao_get_user_info_by_profile_url. An agent can pick the right one 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?

Explicit routing rule: use this tool when a numeric user ID is already available, and use the profile_url variant only when working from a homepage link. This is exactly the when/when-not/alternative guidance the dimension calls for.

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