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

With no annotations, the description carries the full burden and does well: it discloses the 168-hour practical horizon, the capping behavior beyond that, that longer horizons cost more, the data lineage (NWS-derived, bias-blended with a calibrated station model), and the default unit. It omits error behavior and the fact that the schema permits up to 240 hours despite the stated 168 cap.

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?

Front-loads the core capability and coordinates, then layers source, units, and cost/HTTP details. The bracketed pricing/HTTP block is dense but earns its place given no other structured field conveys it.

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?

There is no output schema and no annotations, so the description compensates by enumerating the returned fields (temperature, feels-like, precipitation probability/amount, wind, gusts, humidity, cloud cover) and disclosing the cost model. This is close to sufficient for correct invocation, lacking only explicit alternatives guidance.

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 0%, so the description must compensate, and it largely does: it establishes lat/lon semantics ('exact lat/lon'), the hours horizon and its cost curve, and the units default with the metric alternative. The 168 vs 240 hours mismatch slightly muddies the hours parameter.

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 ('Hourly point forecast') and scopes it to 'any coordinate,' which cleanly distinguishes it from the fixed-city siblings like weather_forecast_nyc. An agent can identify what it produces and when it applies 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?

Usage is implied by the coordinate-based framing (use this when you have arbitrary lat/lon versus a named city), but it never explicitly names an alternative or states when-not to use it. No comparison to weather_forecast-window or the city-specific tools is given.

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