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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and open-world behavior are covered. The description adds genuinely useful extra context: no pagination support and no user/content details in the response, which prevents the agent from attempting page_token pagination or expecting rich entities.

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 compact sentence that front-loads what is returned and appends two scope limitations. Every clause earns its place; there is no filler.

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?

An output schema exists, so return-value shape need not be described, and the description still usefully states the response scope and the absence of pagination. For a single-parameter, annotated, output-schema-backed tool this is essentially complete, though it could note response size or rate limits.

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 itself documents the keyword parameter thoroughly (examples, and prohibitions on links/user IDs/page_token). The description adds no further parameter meaning, so the baseline of 3 is appropriate when the schema does all the work.

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: retrieving the Toutiao search-box suggestion words for a keyword. It further distinguishes itself from siblings by asserting it does NOT return user or content details, which separates it from toutiao_search_users and toutiao_search_posts 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?

The exclusions ('不返回用户或内容详情') implicitly route the agent: for user or post data, use the other search tools. However, no alternative tool is named explicitly and there is no positive statement of when to prefer this over, say, the hot-search list. Clear context, but not full when/when-not/alternative guidance.

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