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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety posture is covered. The description adds genuine behavioral detail beyond them: results reflect currently trending terms (freshness) and the endpoint is non-paginated, which the agent could not infer from the empty schema.

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 leads with the payload returned and immediately follows with the two scope limits. No filler, no redundancy; every clause carries information an agent needs.

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?

Output schema exists, so return-value structure need not be described, and there are no parameters to document. The description supplies what the structured fields cannot: what is returned (terms + heat) and the two hard limits (no video list, no pagination).

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?

The tool takes zero parameters, so there is no parameter semantics to explain; schema coverage is 100% and the schema is an empty object. Baseline 4 applies, with no misleading parameter claims in the text.

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: fetching Haokan Video's current hot search terms and their heat values. It also pre-empts confusion with the video-list siblings by explicitly saying it does not return a popular video list, though it names no sibling tool directly.

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 two concrete exclusions that steer correct use: no hot video list and no pagination support, which tells the agent this is a single-shot keyword endpoint. It stops short of naming a preferred alternative for video lists (e.g. haokan_search_videos), so it is guidance-by-exclusion rather than full when-to-use routing.

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