youtube_list_captions

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

No annotations are provided, so the description carries the full burden. It discloses OAuth requirement and ownership constraint, which is helpful. However, it doesn't describe what the response contains (list of caption track metadata?), pagination, or whether caption tracks exist for all videos. For a list operation with no annotations, it provides partial but not comprehensive behavioral context.

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?

Tight and compact: three short lines plus an Args section. Every sentence earns its place - purpose, auth requirement, scope constraint, and parameter doc. No filler or redundancy.

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?

Single simple parameter with no output schema, so structural complexity is low, which helps. However, for a read operation with zero annotations and no output schema, the description should say more about what gets returned (caption track list with languages/formats?), whether it works for videos without captions, and possible error states. It's adequate for basic selection but thin on behavioral detail.

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?

Only one parameter, video_id, with 0% schema description coverage. The description mentions 'video_id: YouTube video ID' in the Args section, which adds the decoding that it's a YouTube video ID. This adds some value beyond the bare schema (title 'Video Id'), though it's minimal. The parameter is self-evident from naming.

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?

Clear verb+resource: 'List available caption tracks for a video you own.' It specifies it lists caption tracks for a video, distinguishing it clearly from youtube_get_transcript (which presumably retrieves a transcript) and youtube_list_videos. It's specific about scope (videos you own). Not a 5 because it doesn't explicitly contrast with the transcript tool.

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?

States it requires OAuth and only works for videos on the authenticated user's channel, giving clear context on when it's applicable. It doesn't explicitly name alternative tools like youtube_get_transcript, but the ownership constraint provides useful exclusions. Doesn't mention alternatives explicitly, so not a 5.

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