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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds value beyond that by naming the upstream source (AAA), disclosing the data cadence (daily), the unit (per gallon), and the presence of a source date in the response. It does not discuss caching, staleness thresholds, or pagination, which keeps it short of a 5.

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?

One sentence, zero filler, with the resource and scope front-loaded and the source and date caveat trailing. Every clause earns its place.

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?

For a single-optional-parameter read-only tool with no output schema, the description covers what is returned, at what granularity, in what unit, and from which source. The one residual ambiguity is whether the statewide average is still included when an island filter is passed, which matters for interpreting results.

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% and the single optional parameter's allowed values (oahu, maui, big-island, kauai) are already spelled out in the schema. The description restates the same island set in prose, adding marginal meaning but nothing about default behavior or whether the statewide average is still returned when a filter is applied. Baseline 3 applies when the schema carries the parameter documentation.

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?

The description states a specific resource (daily average gas prices per gallon), a precise scope (statewide plus Oahu, Maui, Big Island, Kauai), and a source (AAA). It is trivially distinguishable from the sibling tools, which cover jellyfish alerts, decision briefs, visitor alerts, and planning tools. It stops short of a 5 only because it is phrased as a data noun phrase rather than an explicit action.

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 explicit when-to-use or when-not-to-use guidance, and no mention of what happens if the optional island filter is omitted. Usage is only implied: an agent can infer that the tool returns all islands by default and narrows when the filter is supplied. No alternative tools are named or ruled out.

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