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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=true, so the safety profile is covered. The description adds the conditional usage context (reply_count > 0) but doesn't disclose other behavioral traits like pagination behavior or the compact vs. expanded response format, which are partially covered by the schema's expand parameter description. No contradiction with annotations.

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, concise sentence that front-loads the key purpose and the critical usage condition. Every word earns its place, and it avoids redundancy with the 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?

For a read-only list tool with a rich schema (100% parameter coverage) and annotations covering safety, the description is mostly complete. The only minor gap is that it doesn't explicitly state the return format or pagination behavior, but the schema's expand and cursor parameters already cover those details. The conditional usage guidance is a strong addition.

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 all five parameters are documented in the schema. The description itself doesn't add parameter-level meaning beyond the schema, but the schema already provides detailed descriptions for id, count, cursor, expand, and comment_id. The description's mention of reply_count indirectly relates to the comment_id parameter but doesn't add new semantic value.

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 tool's function: retrieving replies under a comment. It also references the sibling tool tiktok_video_comments, which helps distinguish it from other TikTok tools. However, it doesn't explicitly name the resource as 'comment replies' in a fully standalone way, and the title 'Comment replies' is somewhat generic.

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 provides explicit guidance on when to call this tool: only when tiktok_video_comments reported reply_count above 0. This is a clear condition that helps an agent decide whether to invoke this tool, and it implicitly distinguishes it from tiktok_video_comments.

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