fuel_cost

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

With no annotations, the description carries the full burden of behavioral disclosure. It does mention the $0.001 USDC cost, which is useful transparency, but it omits any description of what the tool does, side effects, authentication requirements, or return behavior.

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?

The description is very short and front-loads the tool name and cost information in a single sentence. Minor redundancy exists between 'fuel cost' and 'Other Utilities tool,' but there is no unnecessary verbosity.

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 and a generic params object, the description leaves the core function completely unknown. The name 'fuel cost' and the payment line are insufficient for an agent to correctly select and invoke the tool or interpret its result.

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 coverage is 100% because the single 'params' wrapper is documented as 'Tool parameters as JSON object,' but this adds no concrete meaning. The description does not enrich parameter understanding, so it meets the baseline for high schema coverage.

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 restates the tool name and labels it 'Other Utilities tool' without any verb or functional explanation. It does not clarify whether fuel_cost calculates fuel expenses or is merely a paid utility, leaving the agent unable to distinguish it from sibling tools.

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?

The description provides no guidance on when to use this tool versus alternatives. The only contextual hint is the x402 payment requirement, which implies a paid call but does not indicate appropriate use cases.

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