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 only that it returns a single record; it says nothing about return cardinality edge cases, missing-ID behavior, or whether output schema carries the rest. Adequate but thin given annotations do the heavy lifting.

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?

Three short sentences, front-loaded with the purpose and ending with the routing hint. Efficient, though the reference to 'dataset id enum value `youtube-creators`' is slightly confusing since no such parameter exists on this tool.

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 annotations covering the safety profile, the description need not explain returns. It covers purpose, the required parameter, and the sibling alternative, leaving only minor gaps in edge-case behavior.

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 description merely restates the channel_id example already present in the schema. It adds no format or constraint detail beyond what the structured field provides, 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?

States a specific verb and resource ('Returns one YouTube channel record by channel id') and scopes it to the youtube-creators dataset. It clearly distinguishes itself from the search sibling, so an agent can route correctly without opening either schema.

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?

Explicitly names the alternative ('Use datasets_youtube_creators_search to search the YouTube creators dataset'), implying this tool is for single-record lookup by known ID. It does not spell out exclusions (e.g., 'do not use when you only have a name'), so it falls short of a full when/when-not treatment.

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