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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that results are paginated and that the ID must be a top-level comment rather than a reply's own ID, but both of those facts are also spelled out in the schema's field descriptions, so the incremental behavioral value beyond structured data is modest and it says nothing about ordering or result size.

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 front-loaded sentence that leads with the operation and parameters, then adds the sibling reference as a semicolon clause. There is no filler, though the semicolon-joined tail packs three separate ideas and would read slightly better as two clauses.

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?

The tool is a read-only paginated list with a complete input schema, full annotation coverage, and an output schema, so the description does not need to explain return values. Purpose, identifier provenance, pagination, and the alternative entry point are all present, leaving nothing an agent needs in order to call it 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%, with url, comment_id and page_token each documented in detail, including the expected URL format and the continuation-token contract. The description restates the provenance of comment_id but adds no syntax, format, or edge-case information the schema does not already contain, so it sits at the baseline for a fully documented schema.

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?

The description names a specific verb and resource (读取完整回复列表 / read a complete reply list) plus the two identifiers it keys on (video page URL and top-level comment ID), so the agent knows exactly what the call returns. It also names the sibling entry point haokan_get_comment_replies_by_video_id, making it distinguishable from the near-duplicate tool without opening a 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?

It states where comment_id comes from (the video comment list) and points at the alternative entry point for the video-ID path, which tells the agent how to pick between the two near-identical siblings. It stops short of an explicit rule such as 'use this tool when you have a URL, otherwise use the video_id variant', leaving the selection slightly inferential.

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