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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint=false, so safety is covered. The description adds genuinely useful behavioral detail beyond that: token-based pagination via nextPageToken and the fact that only the first page of top-level comments returns the `post` object. It does not mention rate limits or auth requirements, keeping it at a 4 rather than 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?

A single, front-loaded paragraph that opens with the core purpose and then layers in return fields and pagination. It is efficient and wastes little, though the dense enumeration of returned fields is longer than strictly necessary.

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?

There is no output schema, so the description must carry the return-value burden, and it does: it enumerates comment fields (text, likes, timestamp, reply count, author details, links) plus the post metadata on the first page. Combined with pagination guidance, an agent has everything needed to call and interpret results.

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 documents videoId, commentId, and nextPageToken. The prose restates their behavior (numeric video id, replies switch, next-page token) but adds no syntax or format detail the schema lacks, matching the baseline 3 when the schema does the heavy lifting.

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 and resource ('Fetches the comments on a public TikTok video') and explicitly distinguishes two operating modes: top-level comments by videoId vs. replies to a comment when commentId is given. This cleanly separates it from siblings like tiktok_posts and tiktok_search without requiring schema inspection.

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?

Gives clear usage contexts ('sentiment analysis, engagement research, building comment datasets') and points to the posts/search APIs as the upstream way to discover a video. It lacks an explicit when-not or alternative-selection rule (there is no tiktok-comments sibling to route against), so it falls short of a full 5.

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