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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds two genuinely useful behavioral facts not in the structured fields: only public playlists are accessible, and each call costs 20 points. It still doesn't say anything about how the video list is ordered or truncated beyond the count cap.

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?

Front-loaded and short: purpose first, then the returned fields, then cost. The only waste is the Korean sentence restating the identical English content verbatim, which adds length without new information for a non-Korean reader.

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 usefully enumerates what comes back (title, channel, video count, video list), and the annotations plus the cost/access notes cover the rest of what an agent needs. Minor gaps remain on result ordering and behavior for private or invalid playlist URLs.

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%, with both url and count fully documented in Korean including format examples and the 1-200 range with a default of 50. The description adds no parameter-level detail beyond the schema, 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 (look up) and resource (public YouTube playlist) and even enumerates the returned fields (title, channel, video count, video list). It does not, however, explicitly distinguish itself from close siblings such as youtube_channel, youtube_metadata, or youtube_subtitle_list, so an agent must infer the boundary.

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: the word 'public' signals that non-public/unlisted playlists are out of scope, and the schema shows a playlist URL or ID is required. There is no explicit when-to-use statement and no named alternative for related lookups (e.g., youtube_channel for channel data).

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