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

With no annotations, the description carries the full behavioral burden and does most of it: it names the data source, the monthly granularity, the ≥100 monthly-arrival inclusion threshold for quiet mode, the sort direction, and the presence of a page_url/per-item url for sourcing. It even supplies the caveat the agent should relay about monthly aggregates differing from point-in-time congestion; what's missing is any note on result shape beyond the URLs or on response-time/rate characteristics.

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?

It is front-loaded with purpose, then mode semantics, then category handling, then the caveat/link guidance — a sensible order with no filler. It is a dense single paragraph, and the agent-directed 'relay this to the user' sentences add length, though they earn their place by shaping output behavior.

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 5-parameter, zero-annotation, no-output-schema tool, this is nearly complete: every parameter is touched and the return surface is partially described via page_url and per-item urls, with a mandated caveat about data granularity. It stops short of describing the record fields an agent would need to summarize results meaningfully.

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 baseline is 3, but the description adds real meaning on top: the quiet-mode threshold and the practical 'fewest tourist arrivals' ordering, plus concrete category examples (카페, 쇼핑, 자연관광지, 해수욕장) that go beyond the schema's shorter example list. It does not explain region matching behavior, which the schema only partially covers.

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 uses a specific verb and resource (find less-crowded places in Jeju) and immediately qualifies it with the data's granularity: individual-destination navigation arrivals, monthly, split by tourist vs. resident. It also distinguishes itself from the sibling list_categories by naming it as the route for enumerating categories, so an agent can route correctly without opening the 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?

It states explicitly when to use quiet mode ('when looking for a calm alternative to a crowded attraction') versus busy mode ('tourist-arrival top ranking') and points to list_categories=true for the full category list. The only absent element is an explicit when-not-to-use, which is minor given how concretely the two modes are framed.

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