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

Annotations already establish read-only, closed-world behavior, so the bar is lower. The description adds useful framing: results are ordered newest first and subscriptionPlatforms carries residual availability for departed titles, but it does not state that the response contains two separate lists (arrivals and departures) despite the 'per list' limit parameter implying 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?

Two sentences, front-loaded with the scope and ordering, then a single clarification about departures. No filler and nothing buried.

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 no output schema and three fully documented parameters, the definition covers the essentials, but it omits the shape of the return value — particularly that arrivals and departures appear as distinct lists, which the 'per list' parameter language hints at but never explains.

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 documents days, limit, and platform including enum values and ranges. The description adds no further parameter semantics such as how the day window is computed or whether the platform filter applies to both lists.

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 resource (titles that arrived on or left Korean OTT subscription services) with clear bidirectional scope and ordering. It does not explicitly differentiate itself from the sibling new_releases, which likely overlaps with the 'arrived' half, so the distinguishing line is left to inference.

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?

No when-to-use guidance and no alternatives named; the second sentence only explains how to interpret a field for departures, not when to pick this tool over new_releases or where_to_watch. The agent must guess the usage boundary.

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