Open-Meteo Weather: forecast

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real context beyond that: the returned fields (temperature °C, humidity, wind km/h, WMO code, per-day max/min and precipitation mm) and that values are in the location's local timezone. It doesn't discuss rate limits or error behavior for invalid coordinates, keeping it short of a 5.

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?

Three tight sentences: purpose first, routing prerequisite second, return shape third. No filler and no repetition of schema bounds.

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 no output schema, the description carries the return-value burden and does so by naming the metric set, units, and timezone behavior. Combined with full schema coverage and read-only annotations, an agent has everything needed to call it correctly.

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 latitude, longitude, and days are fully documented with ranges and defaults. The description reinforces the coordinate-based input and the units of the returned values but adds no syntax or format detail about the parameters themselves, so the baseline 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?

States a specific verb and resource ('Get current conditions and a daily forecast') plus the input mode ('a location given by coordinates'). It also implicitly excludes the reverse geocoding case by pointing at geocode_search, so an agent can separate it from siblings without opening the schema.

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?

Explicitly names the prerequisite case: if you only have a place name, call geocode_search first. That is a concrete when-to-use/when-to-route-elsewhere instruction, exactly the kind of routing guidance an agent needs.

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