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

With no annotations, the description carries the burden and does disclose real behavior: the exact endpoint (GET /v1/forecast/window), a $0.02 x402 price, the docs URL, and the full set of returned metrics. It stops short of stating rate limits or error/timezone behavior, but the payment and endpoint disclosure is meaningful operational context.

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?

Front-loaded with the core value proposition, then the metric list, then the audience. The field enumeration is slightly redundant with the earlier 'rain odds, temps, comfort' phrasing, but overall it is tight and every sentence contributes.

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 4-parameter tool with no output schema and no annotations, the description compensates well by enumerating the return payload (rain probability, precip, temp range, gust, comfort index, verdict) and disclosing the price. Missing rate-limit or error context is a minor gap given the otherwise thorough disclosure.

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 50%: start/end are well documented in the schema (defaults included), while lat/lon have no descriptions beyond numeric bounds. The description adds the coordinate-based scope and the ≤12-hour constraint, which partly compensates, but the lat/lon semantics and timezone handling remain undocumented.

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: it 'summarizes a ≤12-hour window at a coordinate' into named decision-ready metrics plus a verdict. It implies differentiation from the city-named siblings by taking a coordinate and an arbitrary window, but it never names the closest alternatives (weather_forecast-point, weather_forecast-probabilistic) to make that contrast explicit.

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?

'Built for agents planning events, deliveries, and travel' gives a clear usage context, so the when-to-use is implied. However, there is no when-not guidance and no alternative tool is named, leaving the agent to infer how this differs from the point or probabilistic forecasts.

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