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

Annotations already cover the safe read profile (readOnlyHint=true, openWorldHint=true), and the description adds real value by disclosing the credit economics: 1 credit base plus 1 credit per item fetched up to page size, and that extra_fetch fills exact view count, publish date and duration. The cost wording is slightly garbled ("Costs 1 credit per item fetched, up to the page size. Costs 1 credit.") and pagination behavior via cursor isn't described.

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?

It's short and front-loads the purpose, but the closing pair of sentences redundantly restates the cost after already explaining per-item cost in the same paragraph, and the tab sentence is split awkwardly from the credit details.

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?

For a paged list tool with no output schema, the agent still lacks the return shape (what fields a list item carries when not extra-fetched), how cursor pagination terminates, and coverage of the streams tab and cache_max_age. Cost behavior is the one area that is 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 60%, and the description only explains `tab` (videos/shorts) and `extra_fetch` on top of what the schema already says. It omits the `streams` enum value entirely and says nothing about `cache_max_age`, which has no schema description at all.

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?

"Recent public uploads for a channel" is a specific verb+resource statement, so an agent can tell this lists a channel's content. It stops short of differentiating itself from the close siblings youtube_channelShorts and youtube_channelLives, even though the tab enum overlaps with both.

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?

It says to use `tab` to switch between videos and shorts, which gives implied routing. But it never states when to prefer this tool over the dedicated youtube_channelShorts or youtube_channelLives tools, and it gives no guidance on when extra_fetch is worth the extra credits beyond a cost statement.

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