List Captions

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

Annotations already declare readOnly, idempotent, non-destructive, so the safety profile is covered. The description adds real context beyond that: quota cost (50 units) and the ownership constraint on transcript download. It doesn't mention ordering or rate-limiting beyond quota, keeping it just short of a 5.

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: what is returned, the access scope, and the quota cost, with no filler. The informational content is front-loaded before the quota note.

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?

An output schema exists, so return values needn't be re-explained, and annotations cover the safety profile. The description covers access scope and quota, leaving only minor gaps like track ordering or whether an empty result is possible.

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?

Schema coverage is 100%, with 'video' documented as 'Video ID or URL' and 'my_channel' fully explained, so the baseline is 3. The description adds no syntax or format guidance beyond what the schema already provides.

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 definition names the resource (a video's caption tracks) and enumerates the returned fields (language, name, auto-generated flag), so an agent knows exactly what this call produces. It distinguishes itself implicitly from transcript download in the sibling list, but doesn't call out upload_caption/update_caption/delete_caption by name.

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 establishes scope ('works on any public video') and a permission nuance (only the owner can download a transcript), which implies you use this to enumerate tracks before fetching a transcript. There is no explicit when-to-use/when-not or named alternative such as get_transcript, so the routing is left to inference.

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