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 metric units, the 168h horizon cap, the calibration provenance difference (empirical for temp, NWS-derived approximations for precip/wind), a method label in the response, and a per-call price via x402. Return shape beyond band definitions and auth mechanics are not detailed, but the behavioral profile is unusually rich.

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 resource and bands, then units, provenance, caps, and an HTTP/cost trailer. Dense but nearly every sentence earns its place; only the bracketed endpoint/pricing metadata is somewhat ancillary to selection.

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 tool with no annotations, no output schema, and 0% schema coverage, the description supplies provenance, units, limits, and cost. It is close to sufficient, though it does not reconcile the stated 168h cap against the schema's 240h maximum, which could confuse an agent.

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 0%, so the description must compensate. It names the variable enum values (temp, precip, wind) and constrains the horizon, but never explains lat/lon semantics, the hours parameter by name, or its 72h default, leaving gaps for a 4-param tool.

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 resource (hourly p10/p25/p50/p75/p90 bands) for a specific set of variables (temp, precip, wind) at a coordinate. The phrase 'reason about uncertainty, not just point values' implicitly distinguishes it from point/window forecast siblings without ambiguity.

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?

Gives clear when-to-use framing ('reason about uncertainty, not just point values') and states the horizon cap. It does not explicitly name an alternative tool for point forecasts, so it falls short of a full when/when-not/alternatives statement.

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