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

With no annotations, the description carries the full burden and does well: it discloses the data provider, update cadence (issued 8 times a day), grid resolution, the x402 payment requirement and price ($0.0045 USDC on Base or Solana), and that out-of-domain requests return 400 without charge. Missing only rate limits/response latency.

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 when-to-use clause is front-loaded, followed by tight Data/Input/Output/Example/Price segments that are easy to scan. It is dense but nearly every clause carries information an agent needs; the example URL is the only borderline-redundant element.

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 enumerates the return payload (hourly then 3-hourly temperature, sky, precipitation type/probability, rain/snow amounts, humidity, wind, daily min/max) and covers pricing and error behavior. It is nearly complete for a two-parameter point forecast; only units for wind and response size are 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 100% and both parameters are already documented with WGS84 format and KMA domain bounds, so the baseline is 3. The description reinforces 'WGS84 decimal; Korea only' and adds a concrete example query string, but contributes no semantics beyond the schema.

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+resource (official weather forecast), the exact geographic scope (a point in South Korea), the horizon (~3-5 days), and the source (KMA village forecast on a 5 km grid). This clearly separates it from the sibling weather_global without needing to open either 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?

Opens with an explicit 'Use when you need...' trigger plus the 'Korea only' constraint, which is clear usage context. It stops short of naming weather_global as the alternative for non-Korean points, so the exclusion is implied by geography rather than stated.

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