Get YouTube Transcript

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

Annotations only cover the safety profile (readOnly, openWorld, non-destructive), and the description adds real behavioral detail on top: it reads existing captions rather than transcribing, the language match is exact with no fallback, and output is timestamped lines. It does not mention rate limits or failure modes beyond a missing track, which keeps it from 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?

Front-loaded with the core action in the first clause, followed by input, output, and failure semantics in a compact block with no filler. The middle sentence is long and strings several points together, which slightly hurts scannability but wastes no words.

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?

With no output schema, the description properly covers the return shape (timestamped lines) plus the input forms and error behavior, which is most of what an agent needs for a two-parameter fetch tool. The only real gap is not pointing at the sibling language-listing tool for discovering a valid track.

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 both parameters documented including examples, so the schema does the heavy lifting. The description reinforces that language codes must be exact ISO 639-1/BCP-47 with regional or script subtags and notes the videoIdOrUrl forms, but adds no format or edge-case detail the schema lacks.

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?

States a specific verb and resource ("Fetches and returns publicly available YouTube caption tracks") and draws an explicit boundary against the most likely confusion point with "it does not transcribe audio." An agent can distinguish this from summarize_youtube_transcript and list_youtube_transcript_languages without opening any schema.

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?

Gives clear usage context: which inputs are accepted (URLs or raw video IDs), what language codes are valid, and what happens on failure (error instead of a substitute language). It stops short of naming the sibling tools, so it never explicitly says to call list_youtube_transcript_languages first to discover an available track or to use summarize_youtube_transcript for a digest.

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