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

The description usefully discloses that results are ranked by relevance, and that a video lacking the query term in its title is normal — a non-obvious behavioral trait. The readOnlyHint annotation already communicates safety, and the description adds meaning beyond it.

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 brief, focused, and front-loaded with the core purpose. Every sentence contributes useful information without redundancy.

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 available and all parameters documented, the description covers the key behavior and quirk sufficiently. It could mention pagination specifically, but next_page_token and the output schema already provide that context.

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?

The input schema has 100% parameter description coverage, so the schema already explains all parameters. The description adds semantic nuance about relevance ranking for the query parameter, which is helpful but not necessary.

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 states a specific verb ('Search') and resource ('videos inside one channel'), clearly distinguishing it from broader search tools like search_youtube or list-style tools. The mention of YouTube's native relevance search adds further precision.

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 gives clear context that this tool is for searching within a single channel, which implicitly differentiates it from playlist or global YouTube search. It does not explicitly name alternatives or exclusions, but the channel-scoped framing is strong enough.

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