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

Annotations already establish that this is read-only and non-destructive. The description adds useful behavioral detail by disclosing the returned data categories (temperature, precipitation, visibility, wind), which is not present in the annotations or schema. No contradiction; it could add units or date-range behavior but is not misleading.

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 tight, front-loaded sentences. The first states the action and scope; the second enriches with concrete output details. No filler, no repetition of schema information, and every sentence contributes to an agent's understanding.

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 three-parameter read-only tool with no output schema and full schema coverage, the description is sufficient: it explains the purpose, the planning context, and the kind of data returned. Minor gaps like units, forecast granularity, or date-range behavior are not critical given the tool's simplicity and the sibling-tool pattern.

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 all three parameters (location, start_date, end_date) are already documented. The description adds conceptual context linking 'flight destinations' to location and 'travel dates' to start/end dates, but it does not provide any format or constraint details beyond the schema. This matches the baseline for full schema coverage.

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 opens with a specific verb ('Get weather forecast') and a clear resource ('flight destinations and travel dates'), and the flight scope distinguishes it from the sibling weather tools (bus_weather_forecast, car_weather_forecast, hotel_weather_forecast). It also names the key weather elements returned, leaving no ambiguity about what the tool does.

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 gives clear context—'for flight destinations and travel dates' and 'help plan air travel safely'—making it obvious when to choose this over the ground-transport weather siblings. However, it does not explicitly name alternatives or state when not to use the tool, so it falls just short of explicit routing guidance.

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