Cheapest fuel stations near the car

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

The annotations already mark the operation as read-only, non-destructive, and idempotent. The description adds useful beyond-annotation context: the data source is the French government open-data feed, the server must be started with a specific flag, and the search anchor is the car's last parked position. Nothing in the description contradicts the annotations.

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 compact and front-loaded: core behavior first, use case second, then the prerequisites. Every sentence contributes useful selection or invocation information, and there is no redundant restatement of schema fields.

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 read-only lookup with fully documented parameters and an output schema, the description covers what an agent needs: user intent, fuel type, location anchor, France-only restriction, and the server flag. The 'cheapest' wording sufficiently conveys the result-ordering intent without needing to restate the output schema.

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 schema already documents fuel enum values, default limit, max limit, radius bounds, and defaults. The description adds no parameter-specific semantics beyond the phrase 'given fuel', so the baseline score of 3 is appropriate.

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 opens with 'Cheapest stations selling a given fuel around the car's last parked position', which clearly identifies the resource, the search scope, and the ordering criterion. It is immediately distinguishable from the sibling tools, which are vehicle status/control operations, not fuel-price lookups.

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 'Use for:' line explicitly frames the intended user query: 'where can I fill up cheaply near the car?'. It also gives an important geographic boundary ('France only') and a server prerequisite ('--addresses fr'). It does not discuss exclusions or alternatives, but no sibling tool is a plausible alternative for this task.

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