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

Annotations already declare readOnly/idempotent/non-destructive, so the description wisely spends its words elsewhere: the direction of the metric, the ~30-day horizon, and the hard requirement that names be in Korean (a real failure mode for callers). Pagination behavior and the full returned field set are left unstated.

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?

Three compact sentences: definition, intended use, then the prerequisite caveat. Front-loaded and every sentence carries distinct information with no restatement of the schema.

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, five-optional-parameter lookup with no output schema, the description covers what is being returned (daily crowd level via cnctr_rate), the time range, and the naming constraint. Remaining gaps are minor: whether results are per-spot-per-day rows and how limit interacts with the ~30-day window.

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 baseline is 3; the description earns above that by adding operational meaning not in the schema — that poi_name/signgu values must be Korean and must be sourced via search_places with locale 'ko' rather than transliterated by the agent.

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 ('Daily crowd-level forecast'), scopes it geographically and temporally ('Korean tourist spots over the next ~30 days'), and defines the core metric ('cnctr_rate, higher = busier'). No sibling tool does anything similar, and the reference to search_places for name resolution further separates it from the discovery tools.

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?

'Use it to pick quieter days or spots' names the decision this tool supports, and the prerequisite workflow ('use search_places with locale ko to get the Korean name first') tells the agent what to do before calling. It stops short of explicit exclusions or a named alternative for non-Korean destinations.

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