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

Annotations already convey read-only and idempotent behavior. The description adds useful behavioral detail by specifying the output categories (current conditions, days-ahead forecast, sunset, and daylight remaining). It does not mention potential quirks like timezone or unit assumptions, but for a read-only weather lookup this is acceptable.

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 description is a single front-loaded sentence that communicates the core purpose and key returned fields. The closing phrase 'which is the fact that decides an afternoon outdoors' is mildly redundant color but not excessive, so it remains tightened and efficient.

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 simple two-parameter read-only tool with no output schema, the description provides a reasonable outline of the response content: current conditions, daily forecast, and daylight-related values. It could complete timezone/units details, but these are minor for basic forecasting, and the schema plus annotations carry the safety and parameter burden.

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 100%, so the description does not need to explain lat/lon in depth. The schema entries are minimal (only 'Latitude of the location'), and the description adds nothing about valid ranges, formats, or coordinate precision, so a baseline 3 is appropriate.

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 ('Get') and a resource ('weather forecast for a location'), and enumerates what it returns: current conditions, days ahead, and daylight info. It does not explicitly name and distinguish sibling weather tools (e.g., weather_history, weather_air, weather_marine), but the scope is nonetheless concrete and actionable.

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?

The description implies a primary use case: obtaining current and near-future weather plus the sunrise/sunset daylight detail, with a hint at an outdoor planning scenario. However, it offers no explicit exclusions or comparisons such as 'for past weather use weather_history' or 'for air quality use weather_air', leaving sibling differentiation to inference.

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