list_captions

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explains failure on invalid video ID, returns empty list when no captions exist, and details the return object structure. This is strong transparency, though it omits any mention of authentication, pagination, or permission requirements.

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 well-structured: opening summary, then Args section, then Returns section. It is concise, front-loaded with the key purpose, and every sentence adds value without unnecessary verbosity.

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?

For a simple list operation with two parameters, the description is complete. It covers edge cases (empty list, invalid ID), parameter details, and return format. The presence of an output schema does not create gaps since the description already explains the return object.

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?

The input schema has no descriptions for parameters (0% coverage), but the description fully compensates. It defines 'video_id' clearly and for 'part' explains it is comma-separated, lists valid parts, and states the default. This adds significant meaning beyond the schema.

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 clearly states the tool's function: retrieving a list of caption tracks for a YouTube video. The verb 'Retrieves' and resource 'caption tracks for a YouTube video' are specific, and the tool is distinct from sibling 'download_caption_track' which downloads rather than lists.

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 implies usage by explaining parameters and return behavior, but it does not explicitly state when to use this tool over alternatives such as download_caption_track. It lacks explicit 'when to use' or 'when not to use' guidance, so use is only implied.

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