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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds the billing/rate constraint '[호출당 20포인트]', which is genuinely useful behavioral context not present in any structured field. It still says nothing about pagination or return shape.

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?

Three short, front-loaded sentences with the action first and the cost caveat last. The Korean mirrors the English for audience reasons, which is slight redundancy but not padding.

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 a complete schema and read-only annotations, the definition is callable as-is, but with no output schema it also doesn't hint at what a returned video entry contains, and it leaves the agent to infer how this differs from youtube_search.

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 itself documents both the 'count' range/default and the 'hashtag' format (# optional). The description adds no parameter-level meaning beyond that, so the baseline 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?

States a specific verb and resource: 'List videos on a YouTube hashtag page.' The 'hashtag page' scope distinguishes it implicitly from youtube_search, but it never names a sibling to make the boundary explicit, which keeps it from a 5.

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?

Usage is only implied — an agent can infer you call it when you want videos tied to a hashtag. There is no explicit when-to-use, no when-not-to-use, and no pointer to youtube_search/youtube_channel for the overlapping cases.

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