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

No annotations are provided, so the description carries the full burden of behavioral disclosure, and it discloses nothing: not whether this is a read-only fetch, what happens with an invalid ID, whether authentication is required (the _token parameter hints it is), or whether results are cached or rate-limited.

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?

It is a single short phrase with zero waste, but it is under-specified rather than concise; there is no front-loaded verb phrase or scope statement to earn the brevity.

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 two-parameter tool with a fully documented schema and no output schema, the essentials are technically present, but the description omits every behavioral fact an agent needs: the required auth, what the response contains, and any failure or rate-limit behavior.

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 both parameters are already documented in the schema, including the _token auth parameter and its header alternative. The description adds no meaning beyond the schema, so the baseline of 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 phrase names a resource (YouTube video) and an implicit verb (fetch details), and the platform prefix distinguishes it from the many sibling video tools (bili_video, douyin_video, tiktok_video). However, it never states what 'details' actually comprises or what operation is performed, so it is vague beyond platform scoping.

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?

There is no guidance on when to use this tool versus the 29 siblings, no prerequisites, and no exclusions. The description offers nothing an agent can use to route between yt_video and, say, channels_video or tiktok_video beyond guessing from the name.

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