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

Beyond the readOnlyHint/openWorldHint annotations, the description discloses the 30-minute cache, key-less Open-Meteo backend, and the x402 USDC/USDT payment model with 3 free calls per wallet. These are concrete behavioral details that help an agent anticipate cost, external dependencies, and data freshness.

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 description is compact and front-loaded: the first sentence delivers the core functionality, scope, and data source, while the second conveys the essential payment context. Every sentence earns its place with no redundant phrasing.

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 an 8-parameter tool with optional payment and a default forecast window, the description covers the result type, location forms, unit options, caching, and cost. It could be slightly more explicit about requiring either a location or lat/lon since no parameters are marked required, but the output schema and parameter descriptions cover the remaining details.

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 100%, so the description does not need to compensate for missing parameter docs. It still adds useful meaning by tying temperature_unit to °C/°F, location/latitude/longitude to the two addressing modes, and wallet to the free-tier behavior.

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 clearly states that the tool returns current conditions plus a daily forecast up to 16 days, scoped to any place name or lat/lon, via Open-Meteo. It specifies the resource, the result format, and the input addressing options, making the tool's purpose unambiguous.

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?

The description provides clear context for when to use the tool: when the agent needs current weather or a multi-day forecast for a named place or coordinates. It does not explicitly name alternatives or exclusions, but none of the sibling tools directly compete with this weather functionality.

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