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

Annotations already declare the tool as read-only, idempotent, open-world, and non-destructive. The description adds substantial operational context beyond that: MET Norway caching behavior, pricing per successful call, x402/Solana payment, and the exact HTTPS endpoint. It also lists the returned weather data, which is especially useful because no output schema is provided.

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 purpose is front-loaded and every major clause adds useful information. However, the description is a very dense, long sentence with parentheticals and operational details, making it slightly harder to scan than a more structured breakdown would be.

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 seven-parameter tool with no output schema, the description is complete enough to call correctly: it covers the data source, returned conditions, daily/hourly options, units, timezone grouping, caching, pricing, and the sibling alternative. No critical behavioral or usage gap remains.

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 parameters are already well documented structurally. The description reinforces parameters such as days, hourly, units, and tz, but it largely repeats what the schema already says rather than adding new syntax or constraints. It also does not mention the altitude parameter explicitly.

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 states a specific verb and resource: a worldwide weather forecast by latitude/longitude. It clearly distinguishes this tool from the sibling weather_nws tool by reserving US NWS alerts for that alternative. The data source and scope make the tool's purpose immediately clear.

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?

It explicitly says to use /v1/weather-nws for US NWS alerts, which tells the agent when to choose the alternative instead of this tool. The worldwide latitude/longitude framing also establishes the primary use case without ambiguity.

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