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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so safety is covered structurally. The description adds only the content-type examples as behavioral context; it says nothing about external network calls, result ranking, quotas, or latency. Note the annotation openWorldHint=false is questionable for what is intrinsically an open web search, but that is an annotation defect rather than a description contradiction.

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?

A single sentence with the verb and resource front-loaded and no filler. The parenthetical examples earn their place by scoping the content domain, though the whole description is arguably thinner than the tool's role warrants.

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, return values need not be explained, and annotations cover the safety profile for a two-parameter tool. What is missing is the disambiguation from the many other search-flavored siblings, which is the main thing an agent needs before invoking this one.

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%, so both `query` and `max_results` (including the 1-5 range and default 3) are already fully documented in the schema. The description adds no query-syntax guidance (e.g., channel filters, quoting) and no semantics for what counts as a 'relevant' video, so baseline 3 applies.

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?

Specific verb (Search) plus resource (YouTube) with parenthetical examples of expected content types (interviews, trailers, analysis, music videos), which clarifies it is a video-content search rather than a generic one. It is distinguishable from search_library and search_conversations by the YouTube resource, though it never explicitly contrasts itself with the bare `search` sibling.

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 states no when-to-use or when-not-to-use conditions and names no alternative. With siblings like `search`, `search_library`, and `search_conversations` present, an agent gets no signal about why it would pick YouTube search over those, leaving routing to inference from the name alone.

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