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

Annotations already establish readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely new behavioral context: the per-call cost ('[호출당 20포인트]') and the fact that sorting and filtering are supported, which matters for budgeting and for deciding whether one call suffices.

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 English sentence is front-loaded with the verb, resource, and return fields, and the cost note is appended cleanly. The Korean sentence largely restates the English one rather than adding information, which is mild redundancy but justified for a bilingual audience.

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 correctly compensates by listing the fields returned (title, channel, duration, views, thumbnail) and by noting sort and filter support. It omits pagination or continuation behavior, but for a single-call search tool with fully documented parameters this is close to complete.

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 four parameters carry enums with inline descriptions, so the schema already does the heavy lifting. The description restates sort options and filter categories but adds no syntax, default, or interaction detail beyond the schema, making 3 the correct baseline.

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 ('Search YouTube by keyword') and enumerates the result kinds (videos, shorts, channels, playlists) and returned fields, so the agent knows exactly what this tool produces. It does not explicitly contrast itself with near-neighbors like youtube_channel, youtube_playlist, or crawl_youtube, which keeps it short of 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?

No when-to-use or when-not-to-use guidance is given, and no alternatives are named despite several overlapping siblings (youtube_channel, youtube_playlist, youtube_hashtag, crawl_youtube). The agent must infer that this is the general keyword-search entry point from the description alone.

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