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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered. The description adds genuinely new context: that no authentication is required, and that results carry a `window` and `provenance` dict, signaling the numbers are time-bounded and sourced rather than raw counts.

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?

The purpose sentence is front-loaded, and the [auth]/[output] tags are compact and scannable. Cost: the same purpose sentence is restated verbatim in Korean and English, roughly doubling length without adding information, plus mild markup noise.

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, the description correctly spells out the returned structure (region_cd, region_nm, sido_nm, visitors_cur/prev, delta, rate) along with window and provenance, which is exactly the burden it must bear. The remaining hole is parameter behavior, leaving the definition strong on returns but weak on inputs.

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 0%, so the description carries the burden for `lang`, `sort`, and `limit` — and it says nothing about any of them. The names are largely conventional (limit/sort), but `lang` is genuinely ambiguous (response language vs. region-name language) and `sort`'s legal values are undiscoverable. The output field list only partially compensates.

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?

The description gives a specific verb and resource ("Returns Korean districts with the largest surge in foreign visitors") plus the query intent it serves ("inbound-travel questions"), so an agent can tell this is a surge-ranking lookup rather than a generic recommendation. It does not explicitly contrast itself with the sibling recommend_* tools, so differentiation is only implied by the phrasing.

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?

"For inbound-travel questions" is a real use-case signal, which is more than nothing. However, there is no statement of when NOT to use it, no prerequisites, and no naming of an alternative tool for adjacent needs (e.g., trending places vs. visitor-surge regions).

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