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

Beyond the readOnlyHint/openWorldHint annotations, it discloses a key behavioral boundary: it returns transcript languages but does NOT download the subtitles. It also discloses the cost trade-off compared to get_transcript, which is information not present in annotations, schema, or output schema.

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?

The description is front-loaded with the function purpose and output scope, then immediately provides the routing instruction to get_transcript. Every sentence adds distinct information in a compact form with 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 one-parameter read-only tool with an output schema, the description covers what it returns, what it omits, when to use it, and when to call an alternative. Nothing an agent needs to route the call correctly is missing.

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 description coverage is 100%, so the schema already explains the single parameter. The description reinforces that the call targets 'one YouTube video,' but it doesn't add new syntax, formats, or constraints beyond the existing schema coverage. Baseline 3 is appropriate.

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 clearly names the operation ('Get metadata for one YouTube video'), enumerates the specific metadata fields returned, and explicitly notes it returns transcript languages without downloading subtitles. This distinguishes it immediately from get_transcript, the closest sibling, while also limited to a single video as opposed to list/search tools.

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 an explicit when-to-use rule: 'Use it only when the transcript itself is not wanted.' It then names the recommended alternative with exact parameters and cost implications: 'call get_transcript with video_metadata=true instead — it returns both for one credit, where these are two separate calls and two credits.'

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