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

No annotations are present, so the description must carry the full behavioral burden, but it only states the basic operation plus sorting/pagination. It omits important behaviors such as retrieving replies via commentId, pagination semantics, output shape, or access requirements.

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 core behavior is stated in a single front-loaded sentence. The trailing group and billing notes are small but arguably useful operational metadata, though the group information largely repeats the tool naming convention.

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?

For a moderately simple read-only comments tool, the description plus fully described schema is minimally adequate for selection and invocation. However, there is no output schema and the description does not mention the commentId reply mode or pagination details, leaving gaps.

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%, so the schema already explains all five parameters (videoId, commentId, sortBy, nextToken, lang). The description adds only a high-level mention of sorting/pagination, not enough to raise above the baseline.

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 opens with the specific action 'Retrieves comments for a YouTube video' and explicitly mentions sorting and pagination, making the resource and operation unambiguous. The 'video' scope differentiates it from sibling tools like get_youtube_v3_post_comments.

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?

No when-to-use guidance or alternatives are provided; it simply states what the tool does. The sibling get_youtube_v3_post_comments exists but is never contrasted, so the agent gets no explicit guidance on choosing between comment tools.

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