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

Beyond the readOnly/idempotent annotations it discloses a 5-minute response cache, that a wrong-region call yields 401, and that an account-registered region overrides the region argument so regions cannot be mixed. These are operational traits an agent cannot infer from the schema or annotations.

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 purpose, then constraints, then the sibling reference, then a labeled 'Region 선택' block. Dense but well organized; some repetition of date limits already present in the schema descriptions costs it a point.

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?

For a read-only ranked-list tool with no output schema, the definition covers scope, limits, caching, pagination and region selection. It stops short of describing what the ranked response contains (fields per video), a minor remaining gap.

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 coverage is 100%, so the schema already carries parameter documentation; the description reinforces the date window and pagination semantics. It adds one genuinely new rule not present in the schema — that the account-registered region always takes precedence over the region argument — which earns it above the baseline.

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?

Names a specific verb and resource (영상별 시청 순위 조회) and even the underlying endpoint GET /statistics/content-rank. It explicitly distinguishes itself from the sibling get_statistics_summary_daily by scoping that one to account-wide daily time series.

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?

States the retrieval window constraints (within the last year, max 3 months per query), names the alternative tool for a different need, and gives an explicit decision procedure for the region argument including 'confirm with the user when ambiguous, never guess'.

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