list_languages

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

With no annotations, the description carries the burden. It conveys read-only behavior ('Show') and explicitly says it is not for transcribing. However, it does not discuss edge cases or limitations, so transparency is only basic.

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 with zero fluff. The first sentence delivers the main purpose, and the second gives a practical usage tip, making every word earn 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 one-parameter tool with no output schema, the description lists the expected output components (captions, language, duration, chapters), giving sufficient context without needing deeper details.

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 single parameter url is fully described in the schema as 'YouTube video URL or bare video ID.' The description adds no extra parameter detail, so baseline 3 applies due to high schema coverage.

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 a specific verb ('Show') and resource ('which captions a YouTube video has'), listing the exact metadata returned. Distinguishes itself from the sibling transcribe_video by positioning itself as a pre-transcription check.

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?

Provides clear context: use before transcribing when unsure if the desired language exists. It does not explicitly state when not to use or name alternatives, but the guidance is unambiguous.

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