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

Annotations already cover read-only, open-world, and non-destructive behavior. The description adds value by noting this is a 'metered live-data request,' which warns about cost and data freshness, and it mentions the option to include recent videos. This is useful behavioral context beyond the annotations, though it doesn't detail pagination or error handling, which are partly covered by the output schema.

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 two sentences with no fluff. The primary purpose is front-loaded, and the optional video inclusion is mentioned as a secondary clause. It is efficient and readable.

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 output schema provides return structure, annotations cover safety, and purpose is clear. However, the lack of explanation for video_limit and include_videos leaves a gap in parameter understanding. The description could be more complete by stating that video_limit controls the number of recent videos when include_videos is true, but it does not.

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 only 33% (only 'channel' is described). The description says 'Optionally includes recent videos,' which hints at include_videos, but it does not explain video_limit (e.g., range, default) or how it interacts with include_videos. Given the low coverage, the description should compensate by clarifying these parameters, but it leaves them ambiguous.

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 clearly states the verb 'Fetch' and the resource 'YouTube channel', and specifies three identification methods (handle, channel ID, URL). This differentiates it from siblings like get_youtube_video and get_youtube_channel_transcripts, which focus on videos or transcripts rather than the channel object itself.

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 does not explicitly name alternatives or conditions for using this tool over others. It does mention 'metered live-data request,' which implies cost considerations but provides no direct guidance on when to choose this over, say, get_creator or search_youtube. Usage context is implicit but not explicit.

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