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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so safety is covered. The description adds genuinely new behavioral context: the upstream source (Open-Meteo) and a ~15-minute refresh cadence, which tells the agent how fresh the data is. It stops short of noting that forecast data is conditional/can be absent for some days.

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?

One sentence, front-loaded with the location and altitude, then the returned fields, then provenance and freshness. Nothing is padded or repeated from the annotations.

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?

With an output schema present and one fully documented optional parameter, the description does the remaining work well: it pins the location so the agent never asks for one, and covers source and freshness. Minor omissions (units, that forecast days may be empty) keep it from a 5.

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% and the single optional 'language' enum (de/nl/en, default de) is fully documented in the schema. The description adds nothing about the parameter, so the baseline 3 for schema-covered parameters 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?

States a specific verb+resource ('Current weather in Stuben am Arlberg (1409 m) at the Ski Hotel') and enumerates exactly what is returned: temperature, snowfall, snow depth, weather code with label, and coming days. No sibling tool covers weather, and the fixed location makes the scope unambiguous.

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?

Usage is implied rather than stated: the agent can infer this is the tool for weather questions, and 'when available, the coming days' hints at a limited forecast horizon. There is no explicit when-to-use/when-not guidance or pointer to an alternative (e.g. lift status for ski conditions), which is a real gap in a 17-tool sibling set.

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