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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds that this is a terms aggregation returning counts under search filters, but does not disclose rate limits, that facet must be region or discovery_source (left to schema), or other operational context. Adds modest value beyond structured fields.

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, front-loaded with the core behavior before the usage hint. No filler, though the phrasing 'the related search tool' is slightly vague where a name would be more efficient.

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 read-only/open-world profile. The description supplies purpose and the pairing with search, which is sufficient for an aggregation tool whose parameters are fully documented.

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 the schema already documents all 23 parameters including the required facet. The description only alludes to 'search filters' and 'terms aggregation counts' without adding syntax or meaning beyond the schema. Baseline 3 is appropriate.

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: 'Returns terms aggregation counts for the YouTube creators dataset under search filters.' This distinguishes it from the sibling search tool, which returns documents rather than counts. However, it refers to 'the related search tool' rather than naming datasets_youtube_creators_search, so the differentiation is slightly indirect.

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 usage context: 'Use alongside the related search tool to inspect filter counts under the same query filters.' This tells the agent when to reach for it (to get facet counts matching a query) and implies pairing with search. It lacks an explicit when-not statement or a named alternative.

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