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

With no annotations, the description carries the behavioral burden, and it does well: it discloses the 2-credit cost, no charge on empty results or failures, the 24h cache behavior, and the long-form rejection. It doesn't cover rate limits or auth, but the key operational edge cases for a read-only comments fetch are disclosed.

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 compact and front-loaded: the core scope constraint comes first, followed by cost and caching behavior. There is minor redundancy with the cache parameter's schema description, but the overall size is well controlled and no fluff is present.

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?

The tool has four parameters and no annotations or output schema, but the schema descriptions are rich and the top description adds cost, error behavior, and cache semantics. The only notable gap is the absence of any detail about the response shape beyond the cursor hint, which is not critical for selecting or invoking this tool.

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%, and the schema already documents defaults, max limit, pagination cursor behavior, URI format, and platform matching. The top description adds mostly cost and cache policy, which is useful but not parameter-specific. Since the schema handles parameter semantics fully, a 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 names a specific verb and resource: getting comments on a YouTube Short, with an explicit ≤3-minute constraint. It clearly distinguishes itself from generic YouTube comment tools by rejecting long-form videos, which is relevant given siblings like youtube_comments and youtube_comment_replies.

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?

The description and url parameter give clear guidance: use for Shorts only, long-form returns HTTP 422 and should go to a /v1/youtube/… endpoint instead. The cache=true hint also tells agents when to use the cheaper path. It doesn't explicitly name the exact alternative endpoint, but the routing guidance is strong enough.

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