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

No annotations are provided, so the description carries the full burden, and it does disclose real operational traits: a 3-credit cost regardless of cache hits and a refund on failure, plus the parent_comment_id linkage for replies. It stays silent on rate limiting, auth requirements, or result ordering, keeping it short of a 5.

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?

Three tight sentences: purpose and payload first, the input constraint second, cost/refund last. Nothing is redundant with the schema and no sentence is padding.

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?

With no output schema, the description usefully enumerates the returned fields, and pagination/refresh semantics are covered by the schema's limit/cursor/fresh descriptions. Only minor gaps remain (ordering of comments, whether replies are always included, applicability of the cache to cursor pages).

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 coverage is 100%, so the per-parameter baselines are already documented and a 3 would be the floor. The description adds a genuine cross-field rule ('exactly one of url or id') that the schema's empty required list does not express, so it earns above 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?

States a precise verb+resource ('Fetch comments on one TikTok video') and enumerates the returned fields (username, text, create_time, like_count, reply_count, parent_comment_id), which unambiguously separates it from get_tiktok_video, get_tiktok_videos and get_x_replies. An agent can pick this tool without opening the 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?

The description implicitly defines when to use it (when you have a specific TikTok video and want its comments) and adds the useful constraint 'Give exactly one of `url` or `id`'. However, it never names an alternative tool or states when NOT to use it, e.g. for bulk comment harvesting via search_tiktok, so usage guidance is only implied.

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