Get forecast

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

Annotations already declare readOnly, idempotent, openWorld; the description adds genuinely non-structured context: 'Times are local to the place', which an agent cannot infer from the schema and which matters for interpreting results. It stops short of noting data source, freshness, or rate limits, and the hours/hours interplay is already in the schema.

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 dense sentences with no filler: scope and returns first, prerequisite routing last. Every clause carries information an agent would otherwise have to derive.

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 correctly compensates by enumerating the returned fields for both daily and hourly modes plus the local-time convention. It leaves out units of the returned values and any error behavior for out-of-range coordinates, which is a minor remaining gap for a 7-parameter read tool.

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 every parameter is already documented, establishing a baseline of 3. The description adds that 'hours' only applies in hourly mode and lists which variables each mode returns, but gives no extra detail on units, defaults, or valid ranges beyond the schema.

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 ('Daily forecast') plus horizon (up to 16 days), the exact variables returned, and the optional hourly mode (up to 48 hours). This cleanly separates it from get_current_weather and from search_locations without either schema being opened.

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?

Explicit routing rule: 'Use search_locations first if you only have a place name.', which names the sibling and the condition that selects it. It does not state when to prefer this over get_current_weather, though the daily-vs-current framing makes that largely implicit.

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