Fetch metadata and captions for a YouTube video using its 11-character ID, including title, channel, duration, views, likes, and comments.
Retrieve video metadata & captions. Returns the metadata of a YouTube video by its 11-character id: title, description, channel id and title, publication time, duration in seconds, and view, like and comment counts. Some fields are best-effort.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | YouTube video ID (11-char code) |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the full behavioral burden. It usefully discloses the exact set of returned fields and warns 'Some fields are best-effort', but says nothing about auth requirements, rate limits, or failure behavior for invalid IDs.
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 short sentences, front-loaded with the action and immediately followed by the return payload. It is efficient, though the '& captions' lead is a slightly wasteful/ambiguous claim that the rest of the text does not support.
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 correctly fills that gap by enumerating the returned fields (title, channel, publication time, duration, view/like/comment counts) and flagging best-effort reliability. For a single-ID lookup this is nearly complete, missing only error/rate-limit behavior.
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?
Single required parameter with 100% schema description coverage ('YouTube video ID (11-char code)'). The description restates the '11-character id' detail already present in the schema without adding format examples, URL-handling rules, or validation semantics, so baseline 3 applies.
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 (Retrieve) and resource (video metadata) scoped to a single YouTube video, and names the required identifier. However, the opening phrase 'metadata & captions' muddies the boundary with siblings youtube_captions and youtube_transcript, since captions are not among the listed return fields.
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?
Usage is only implied: the 'by its 11-character id' phrasing signals that you must already hold a video ID (ruling out search-like use), but no explicit when-to-use, when-not, or alternative tool (e.g. youtube_search, youtube_transcript) is named.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.