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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds real context beyond them by disclosing the returned content set (polar lookup, 0.75 default efficiency, VMG/tacking correction, wave derate, non-modelled items, attributions) and the Markdown output form. It does not note length or versioning of the document, keeping it below 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?

Purpose and trigger are front-loaded in the first two lines, and the covered-topics list is informative rather than filler. The topic enumeration is long and slightly list-like, but each item signals a real section an agent can point the user to.

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 zero-parameter documentation tool with an output schema present, the description supplies everything needed: what is returned, in what format, and when to reach for it. It even previews the scope of the content, so an agent knows the answer will cover edge cases like wind against current and short-period chop.

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?

The tool takes no parameters, so there is nothing to disambiguate and the baseline of 4 applies. The description correctly implies a parameterless, whole-document fetch rather than a topic-selective one.

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 — 'Return OhMyWind's calculation methodology as Markdown' — and the format is named up front. It is unmistakable against siblings like get_marine_forecast, get_tidal_stream, or plan_passage, which return data rather than methodology documentation.

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 trigger condition is concrete and even illustrated with example user phrasings ('comment c'est calculé ?', 'is tacking modelled?'), which leaves little ambiguity about when to call. It stops short of an explicit when-not or naming a sibling as the alternative, so it is clear context rather than full routing logic.

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