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

Annotations already cover read-only, open-world and idempotent semantics, and the description adds genuinely new traits: result freshness is limited to recently confirmed docks, distances are straight-line rather than navigable water distance, and hours/prices are absent. The phone number is surfaced as an expected return value, though the rest of the return shape is unspecified.

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?

A single densely packed sentence plus a short caveat sentence; scope, filtering, ordering and limitations are all front-loaded with no filler clauses.

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 carries the burden of describing results, and it does name the phone number, ordering, and the notable missing fields (hours, prices). It stops short of describing the other returned fields (dock name, location/address, fuel types), which slightly limits completeness.

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 all four parameters (lat, lon, limit, diesel) are already documented. The description only indirectly alludes to them via "closest first" and the diesel/gas mention, adding no format or constraint detail 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 (public marina fuel docks in Florida) with a clear qualifier (only recently confirmed ones offering gas, diesel or pump-out) and an ordering rule. It is unambiguous against siblings like boat_ramps or inlet_watch, which cover different facilities.

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?

"Closest first" plus the fuel-type qualifier implies the refueling-planning use case clearly, and "call ahead" tells the agent not to treat hours/prices as answers. It doesn't explicitly name an alternative tool or a when-not-to-use condition, keeping it just short of a 5.

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