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

Annotations already declare readOnly, openWorld, non-idempotent, and non-destructive, so the safety profile is covered. The description adds the useful sequencing context (what to do with the returned urls) but says nothing about rate limits, quota cost, or result ordering.

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?

Two tight sentences: the primary action first, then the follow-on routing. Nothing is redundant and both sentences are actionable.

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 an output schema present and full parameter documentation, the description only needed to cover selection and next steps, which it does. It could note that results feed the list_* tools' url parameter more explicitly, but it is essentially 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 coverage is 100% and every parameter has its own description, so the schema carries parameter meaning. The description only echoes the channel-default behavior, adding little beyond that.

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 ('Search YouTube for channels... or playlists') and explicitly marks channel as the default mode, which cleanly separates it from search_videos and the list_* siblings.

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?

Gives a clear workflow: search here, then pass the returned channel or playlist url to list_channel_videos, list_channel_playlists, or list_playlist_videos. It does not state a negative case (e.g. 'use search_videos for videos'), so a small gap remains.

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