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

Annotations already declare readOnly=true, idempotent=true, destructive=false, so the safety profile is covered. The description usefully adds what the ranking is computed on (cheapest unlimited plan per identical trip length), but says nothing about result ordering beyond 'cheapest first', pagination, or whether countries without available plans are excluded. The trailing '(화면 규칙)' is opaque.

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-loaded and short in absolute terms, but the Korean sentence largely restates the English one, so roughly half the text is duplication that adds no new information. The parenthetical '(화면 규칙)' adds noise rather than meaning.

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 3-parameter read-only tool with no output schema, the description conveys the core intent, the ordering metric, and the trip-length-locking requirement. Enough to call it correctly, though output shape and the 'form' parameter's effect remain unstated.

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 67%: 'days' and 'limit' have descriptions, but the 'form' enum has none. The description reinforces that 'days' must be constant across the comparison, adding a little meaning beyond the schema, but it never clarifies the esim/usim 'form' choice. Baseline 3 is appropriate given partial coverage.

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 ('ranks destination countries by the cheapest unlimited travel eSIM (or SIM) price') plus the equating condition ('for the same trip length'). An agent can distinguish this ranking/comparison operation from sibling 'find_esim_prices' by the ranking framing, though no sibling is named explicitly.

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 or when-not-to-use guidance, and no sibling alternatives are mentioned. The 'for the same trip length' clause hints at the comparison scenario, but the agent must infer whether this or find_esim_prices is the right call.

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