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

Beyond the readOnlyHint/openWorldHint annotations, it discloses source (the channel's public Videos page), a fragility caveat ('YouTube's page layout can change'), and pricing/payment terms ($0.002 USDC per successful call via x402 on Base/Solana/Arc, failed calls uncharged). For a paid, scrape-backed tool that is exactly the behavioral context an agent needs.

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-loads what the tool returns before caveats and cost, and every sentence carries information. The final pricing sentence is dense with three clauses but its content is essential, so the packing is justified rather than wasteful.

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 a single well-documented parameter, the description covers everything else an agent needs: retrieval scope, data source, known limitations, and billing behavior. No material gaps remain.

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 the handle parameter is fully documented with format and example, so the baseline of 3 applies. The description adds nothing about the parameter beyond what the schema already says.

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 — 'latest videos of a YouTube channel' — plus explicit scope ('first page, up to 30') and the exact fields returned. This separates it from siblings like social_youtube_channel_search, social_youtube_comments and social_youtube_shorts without needing to name them.

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?

Exclusions are stated explicitly ('no comments, no subscriber counts and no full history'), which tells the agent when this tool is the wrong pick. It stops short of naming the alternative sibling to use for comment or historical data, so it is clear context rather than full routing.

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