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

Annotations cover the safety profile (readOnlyHint, openWorldHint), but the description adds real behavioral context the annotations cannot: the NOAA buoy is the source, non-US spots fall back to model values and label them as such, and units are metres with feet in brackets. It stops short of error behavior or data-staleness handling.

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-loaded with the payload contents, then provenance caveats, then the input format and units. Three dense sentences with no filler, though the mid-sentence parenthetical list is slightly heavy.

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, so the description carries the return-value burden itself and does so fully — it names every data group (buoy metrics, tides, forecast) and flags the model-vs-buoy distinction. Nothing an agent needs to call or interpret this correctly is missing.

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%, so both parameters are already documented, and the description largely restates them ('Accepts a spot id or name'). It adds only marginal meaning — the forecast length tied to include_forecast and the units convention — so the baseline 3 applies.

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 (conditions at ONE surf spot) and enumerates exactly what is returned — buoy wave data, tides, and a 7-day swell forecast. The singular scope implicitly separates it from surf_search_spots, so an agent can route correctly 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 only implied: the description tells you it accepts an id or name and returns current conditions, but never states when to pick this over surf_search_spots or what happens with an unrecognized spot. No explicit when/when-not guidance is present.

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