list_video_captions

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

Discloses authentication requirement and output structure beyond annotations which already declare readOnlyHint and openWorldHint. Adds value by describing the response's items[].snippet fields.

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?

Two sentences, front-loaded with purpose and auth, then usage guidance. No extraneous information. Every sentence earns its place.

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 tool with one parameter and no output schema, the description covers purpose, auth, output fields, and alternative. No gaps given the complexity.

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 full schema coverage. Description doesn't add new info beyond 'The video ID' in the schema. Baseline 3 as 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?

Clearly states the tool lists available caption track metadata for a video, specifying output fields (language, name, trackKind, lastUpdated). Distinguishes from sibling tool get_video_transcript by directing users to use that for downloading actual text.

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?

Explicitly says use this to discover caption languages and use get_video_transcript to download text, providing clear when-to-use and alternative. Also mentions required authentication (API Key or OAuth).

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