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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and reach profile is covered. The description adds genuine value by disclosing temporal resolution (hourly), the 48-hour window and the upstream data sources (HRDPS/GDWPS, NWS, MET Norway), but says nothing about coverage gaps, caching, or how source selection behaves.

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?

A single, densely packed sentence that leads with the returned variables and front-loads the time window before listing data sources. No filler, though the source list at the end is the least essential element.

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?

For a simple two-parameter read-only lookup with no output schema, the description tells the agent what comes back, at what resolution, over what horizon, and from which providers. Minor gaps: no units for wave height/period and no handling of inland or out-of-coverage coordinates.

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% — both lat and lng are fully documented with ranges and WGS84 conventions — so the baseline of 3 applies. The description adds no further parameter meaning (e.g., whether land coordinates or coastal proximity matter).

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 resource (hourly wind, gusts, direction, temperature, rain, fog, thunder risk) with an explicit temporal scope (next 48 hours) and adds waves. This implicitly separates it from siblings like water_temperature, currents and tide_times, but it never names or contrasts an alternative directly.

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?

The 48-hour hourly horizon implies when the tool is appropriate (short-range marine conditions), which is useful usage context. However, it gives no explicit when-to-use/when-not-to-use guidance and no pointers to sibling tools for other needs.

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