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 useful behavior (explicit nulls when unavailable, source/freshness metadata, timestamp), but the units block about water temperature, visibility, and current sign is unrelated to UV and muddies rather than clarifies this tool's output.

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 purpose in the first sentence and keeps overall length modest. However, the units sentence (ft/kt/F/mi, directions FROM, water temperature, currents) is mostly irrelevant to a UV forecast and consumes a third of the text.

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?

No output schema exists, so the description should describe return shape; it gives some of that (timestamp, source status, explicit nulls, metadata) which is helpful. But it omits the spot/hours parameter details and pads with unrelated unit/convention notes, so an agent still lacks key calling information.

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 carry the parameter burden. It implies a spot (verified) and 'next hours' (hours), but never explains the spot pattern/format, the default of 24, or the 1-168 range, leaving the nested query object largely undocumented.

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: 'UV forecast for a verified spot over the next hours.' This distinguishes it from broad siblings like get_forecast or get_surf_forecast, though it never explicitly contrasts with them and 'verified spot' is left unexplained.

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?

No guidance on when to use this versus get_forecast, get_surf_forecast, or get_conditions, and no note that the spot must already be verified/resolvable. The only hint is the incidental phrase 'verified spot', which is not framed as a prerequisite or an alternative-selection rule.

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