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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description still adds real value: it discloses that satellite clarity is a relative index rather than measured dive visibility, and that unavailable states must be preserved — genuine interpretive caveats beyond the structured fields.

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?

The purpose is front-loaded in the first sentence, followed by compact caveats and a units/return summary. Every sentence carries information, though the units string is dense and slightly list-like.

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 usefully notes what is returned (data plus source/freshness metadata) and enumerates units and direction convention. The main gap is how an agent obtains a valid 'verified spot' identifier, which the sibling list_spots would supply.

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% for the single nested 'spot' parameter, so the description carries the burden. 'For a verified spot' hints the identifier must be validated, but no format, source, or lookup guidance is given to compensate for the total absence of schema descriptions.

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 ('Approximate Gulf Stream edge') plus the required input scope ('for a verified spot'). It is clearly distinguishable from related siblings like get_currents or get_temperature_fronts, though it never names or contrasts with them explicitly.

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 guidance on when to call this versus get_currents, get_water_clarity, or get_temperature_fronts. The note about preserving sample dates and unavailable states is output-interpretation advice, not a use-case or exclusion rule.

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