youtube_video_comments_replies_listList replies to a YouTube comment. Accepts a from video comments. Returns a list (use cursor when paginated).
| Name | Required | Description | Default |
|---|---|---|---|
| cursor | Yes | Comment `repliesCursor` from Video Comments endpoint, or `page.nextCursor` to paginate replies. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, covering safety and non-determinism. The description adds the pagination behavior ('use cursor when paginated') and indicates a list return, but does not add deeper context such as rate limits or data freshness. Doesn't contradict 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 short, but the second sentence 'Accepts a from video comments' is an incomplete fragment that detracts from clarity. The first and third sentences are efficient, but the overall structure is flawed by the typo.
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?
The tool has one parameter and no output schema, so the description should explain that the cursor comes from a prior call to youtube_video_comments_list. This critical prerequisite is not stated, leaving an agent unsure how to obtain the required input. The description also doesn't clarify that replies are nested under a specific top-level comment, which is central to the tool's purpose.
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% and the schema thoroughly explains the cursor parameter (repliesCursor and page.nextCursor). The description adds a broken phrase 'Accepts a from video comments' that is likely a typo for 'cursor' and adds no new meaning; it could actually confuse an agent. Since the schema carries the meaning, the description fails to add value and contains a grammatical error.
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 states 'List replies to a YouTube comment' with a specific verb and resource, clearly distinguishing this from sibling tools like youtube_video_comments_list (which lists comments on a video) and youtube_video_comments_analysis_get (analysis). No ambiguity about what the tool does.
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 no explicit guidance on when to use this tool versus alternatives. It mentions 'Accepts a from video comments' but this is a broken fragment and doesn't explain the need to first call youtube_video_comments_list to obtain a repliesCursor. No alternatives or exclusions are mentioned.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each tool is clearly scoped to a specific platform and action (e.g., facebook_post_get vs instagram_post_get). Descriptions explicitly differentiate similar tools across platforms, and within-a-platform tools like tiktok_search_videos_list vs tiktok_search_hashtag_list have clear disambiguation notes.
All 167 tools follow a strict `platform_resource_action` pattern (e.g., youtube_video_comments_list). No mixing of styles—snake_case throughout, with consistent verb ordering (get, list, search, etc.).
The server has 167 tools, which is far beyond the typical well-scoped range of 3-15. While the broad multi-platform scope justifies many tools, this extreme number makes the tool surface overwhelming and difficult for an agent to navigate efficiently.
The tool set covers a wide range of platforms and operations including profile retrieval, post/video fetching, comments, search, transcripts, and ad library access. Minor gaps exist (e.g., no Facebook events or LinkedIn messaging), but the surface is comprehensive for a read-only data aggregation use case.