List transcript languages

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

Annotations already establish read-only, idempotent, non-destructive behavior, so the bar is lower. The description adds useful output semantics: it flags auto-generated tracks and explains that hasCaptions=false means no transcript exists at all, which is beyond what annotations convey.

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 sentences, each earning its place: the core function, the usage trigger, and a key result field meaning. The most important action is front-loaded and there is no filler.

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 one-parameter, read-only tool with strong annotations and a fully documented schema, the description covers what the tool returns and when to invoke it. No critical information is missing for an agent to select and call it correctly.

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 schema covers the single url parameter at 100%, including a thorough list of accepted URL formats. The description adds no additional parameter-level meaning, so the schema carries the burden and the 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?

The description uses a specific verb and resource: "List every caption track a video offers," and clarifies the auto-generated marking. It differentiates from youtube_get_transcript by positioning this as the survey of available tracks rather than the transcript content itself.

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?

It gives explicit trigger conditions: use after LANGUAGE_UNAVAILABLE or to decide what youtube_get_transcript can return. It names the relevant sibling tool and gives the agent a clear routing decision.

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