tomorrow_forecast

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds nothing on top: it doesn't mention that an api_key is required, whether calls are metered/rate-limited, or what horizon the forecast covers. With annotation coverage this becomes a minor gap, but the description contributes zero behavioral context.

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 short, front-loaded sentence with no wasted words, which is structurally clean. But the brevity here is under-specification rather than efficiency — the size reflects missing information, not discipline.

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?

A 4-parameter, open-world external API call with no output schema and 25% schema coverage needs the description to explain inputs, units, and return shape. The single sentence leaves an agent unable to construct a correct call without guessing at location format and units.

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 only 25% — only 'timesteps' has a description, and that merely restates the enum ('1h or 1d'). The description does not explain the location format (city name, lat/lon, or ID), the accepted values for 'units', or that 'api_key' is a credential the caller may need to supply. With low coverage, the description was expected to compensate and does not.

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?

A specific verb and resource ('Get a weather forecast') plus the provider name ('Tomorrow.io') tell the agent what the tool returns and which API backs it. It does not, however, distinguish forecast from the many weather siblings (weather_forecast, weather_hourly, tomorrow_history, tomorrow_realtime, marine_forecast), so the agent must infer the boundary from the name alone.

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?

There is no statement of when to use this instead of weather_forecast, weather_hourly, tomorrow_realtime or tomorrow_history. The agent gets no exclusions, no prerequisites, and no hint about what inputs produce a useful forecast.

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