Youtube Get Comment Replies

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

With no annotations, the description carries the full burden and does so: it discloses the shared 10,000-unit quota cost per page, the 100-reply page cap, next_page_token pagination, plainText formatting, and that each page costs one unit. It also flags failure behavior for an unknown comment_id ('fails with a not-found error; retrying will not help') and warns that reply content is untrusted user input — unusually rich operational context.

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?

Front-loaded with the core action and the ID provenance before quota, pagination and safety notes; each sentence carries distinct information. It is longer than typical, but the density is high and little is wasted — only the return-field restatement overlaps with the output 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?

Given three parameters, an output schema (so return shape needn't be re-explained), and no annotations, the description covers the gaps that matter: ID provenance, quota/pagination economics, error semantics, and content trust. Nothing needed to invoke it correctly is missing.

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 0%, so the description must compensate, and it does for the critical parameter: comment_id is pinned to a top-level comment ID from youtube_get_comments items[].comment_id and explicitly excluded from being the video ID or a reply's own ID. page_token is implied by the next_page_token mention and max_results' 100 ceiling is echoed ('at most 100 replies'), but the default of 20 and page_token's exact usage are left to the 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?

States a specific verb+resource+scope: 'Get the full set of replies to one top-level comment', with parenthetical return fields. It explicitly distinguishes itself from the sibling youtube_get_comments by explaining that tool's embedded replies sample is truncated, so an agent can pick correctly 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?

Names the selecting condition ('This is the tool for reply text' vs. the truncated sample in youtube_get_comments) and gives an explicit when-not for pagination ('page only if you need the tail'). It also routes the agent to the thread's total_reply_count for sizing, leaving no inference about alternatives.

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