Bright Sky — DWD Severe Weather Alerts for Germany

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: it explains that the tool resolves coordinates to a warn cell, returns an empty list when no warnings are active, requires no API key, and lists the exact alert fields (event type, severity, urgency, certainty, onset/expiry, headline, description, recommended action). This is meaningful behavioral disclosure that helps an agent interpret results.

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, well-structured paragraph that front-loads the core purpose, then lists return fields, then covers edge behavior (empty list), then addresses access requirements (no API key). Every sentence adds information; there is no filler or repetition of schema content.

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 read-only, two-parameter tool with a complete schema and an output schema present, the description covers everything an agent needs: what the tool does, what it returns, how it behaves with no warnings, and access requirements. The output schema handles return-value details, and annotations handle safety. Nothing critical is missing.

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 schema already documents both parameters with examples and ranges. The description adds context by explaining that the coordinates are used to identify the warn cell, which clarifies why latitude/longitude are the only inputs. It doesn't add format details beyond the schema, but the schema is already complete, so the description's contribution is contextual rather than redundant.

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') and resource ('active DWD severe weather alerts and warnings for any location in Germany'), and immediately distinguishes itself from generic weather tools by naming the data source (DWD), the geographic scope (Germany), and the mechanism (warn cell identification). It also enumerates the exact fields returned, making the tool's purpose unmistakable even among many weather-alert siblings.

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 clearly states the tool is for Germany and requires coordinates, and it explains the warn-cell resolution behavior. It does not explicitly name alternative tools (e.g., brightsky.weather.current or metno.weather.alerts) or state when not to use it, but the geographic and data-source constraints are strong enough that an agent can infer when this tool is appropriate.

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