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

Annotations cover readOnlyHint and openWorldHint, so the safety profile is set. The description adds valuable context beyond structured fields: pricing ($0.004 USDC per call via x402), forecast horizon cap (14 days), and supported input modes. It does not mention rate limits or response format, but this is solid added value.

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?

Two dense sentences, front-loaded with the primary function and scope, then fields, then pricing. No wasted words.

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?

No output schema exists, so the description reasonably lists return fields. Covers purpose, inputs, units, forecast cap, and cost. Missing pagination/rate-limit and precise lat/lon expectations keeps it from a 5.

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 60% (params lat, lon lack descriptions; days and units have them). The description clarifies lat/lon vs place-name input modes and 'metric or imperial', which compensates somewhat for the undocumented lat/lon, though it doesn't explain coordinate format or defaults. Baseline 3 improved to 4 for filling the input-mode gap.

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 (current weather and forecast) with explicit scope ('up to 14-day') and enumerates returned fields. Siblings include airquality and solar but not weather, so differentiation is implied by the unique weather domain.

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?

Implies usage context (any place name or lat/lon, metric or imperial) but gives no explicit when/when-not guidance or alternatives (e.g., airquality for air quality, solar for sun data). Adequate but leaves routing to inference.

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