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

With no annotations present, the description carries the full burden and does meaningful work: it discloses the HTTP verb (GET, i.e. read-only), the paid nature ($0.02 via x402), and the default-window behavior when params are omitted. It does not cover rate limits, retry behavior, or response shape in detail, but the safety/payment profile is disclosed.

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 question the tool answers, and the calling convention follows immediately. Slight redundancy between 'Will it rain...' and 'Event-window weather odds for Jacksonville,' but the trailing HTTP/price/docs metadata is compact and earns its place for a paid endpoint.

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 two-optional-parameter, no-annotation, no-output-schema tool, the description supplies the purpose, defaults, cost, and a brief indication of the return (rain probability and expected conditions). Without an output schema it could say slightly more about the returned fields, but the essentials are covered.

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% and both parameters are already documented, including the ≤12h constraint and default values. The description restates the omit-for-six-hours default, which is consistent with the schema but adds no syntax or format detail beyond it, so the baseline of 3 applies.

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 names a specific question ('Will it rain in Jacksonville during your event window'), the resource (event-window rain probability/conditions for Jacksonville), and the geographic scope. It also distinguishes itself from the generic sibling by noting it is 'the same shape as /v1/forecast/window with the Jacksonville coordinates built in,' so an agent can tell it apart from both weather_forecast-window and the point-forecast weather_forecast_jacksonville.

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 states when this is useful ('built for scheduling decisions') and the calling pattern (pass start/end, or omit for the next six hours). It does not explicitly name alternative tools for other cities or point-in-time conditions, but the usage context is clear and unambiguous.

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