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 itself does not add behavioral context such as pagination behavior, response structure, or the non-reusable page token rules; those are deferred to the 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?

The description is a single front-loaded sentence that captures the tool's scope and input types without wasted words. It is appropriately concise because the detailed parameter behavior lives in the input schema.

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 schema and output schema together provide rich context: URL format restrictions, sort enum, opaque page_token constraints, and likely response fields. The main description is sufficient for selecting the tool when given a URL, though it could slightly improve by explicitly calling out the by_id alternative or the top-level-only scope in the tool's own text.

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 thoroughly documents the url, sort_type, and page_token parameters, including the opaque-token rules. The main description adds no additional parameter semantics, so the baseline score of 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?

The description clearly states the action: retrieve a first-level comment list based on a Bilibili video, article, dynamic link, short link, or share text. This precise verb-and-resource phrasing also distinguishes it from the by_id comment tool and the comment-replies sibling.

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 description clearly implies the main use case: when you have a Bilibili content URL and want top-level comments. However, it does not explicitly reference sibling alternatives or state when not to use this tool, even though the schema's url description adds exclusions like 'do not pass BV number, aid, or numeric ID'.

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