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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavior beyond that: the NOAA buoy is the preferred source, and outside the US the 'now' values fall back to model output and are labelled as such. It also pins down units (metres with feet in brackets). No auth or rate-limit notes, but for a read-only status call this is strong disclosure.

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?

Three sentences, front-loaded with what the agent gets back, followed by the fallback caveat and the input/units note. Dense but every clause carries information; only the parenthetical enumeration of buoy fields is slightly list-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 must carry the return-value burden, and it does: it names the data sources, the fields returned, the units, and the degradation case where model values substitute for buoy readings. Nothing an agent needs to call or interpret this tool 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 (spot, include_forecast) are already documented in the schema. The description restates that a spot id or name is accepted and alludes to the forecast, but adds no format, matching, or defaulting nuance beyond the schema. 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 (what the water is doing at one surf spot) and enumerates the returned content: buoy readings, tides, and a 7-day swell forecast. This clearly separates it from surf_search_spots (discovery) and the status tools of other domains, so an agent can route without opening a 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 frames the tool as reporting on 'one surf spot', which suggests it is for a spot you have already identified. It never names surf_search_spots as the alternative for finding spots, nor states any when-not condition. Adequate but leaves routing to inference.

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