Cheapest fuel along a trip

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

Annotations already declare readOnly/idempotent/openWorld, so the bar is lower, yet the description adds real operational context: the call consumes two of the API's 30 route searches per minute, prices are in local currency and cross-border trips mix currencies (pointing to pumperly://exchange-rates). Units differ by fuel (per litre/kg/kWh), which an agent cannot infer from the enum alone.

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 dense sentences with the core action front-loaded before caveats about units, currency, and rate limits. Every sentence carries information; slight density in the pricing sentence but no filler.

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?

An output schema exists so return values need no explanation, and the description covers the remaining unknowns an agent needs: routing behavior, corridor semantics, sorting default, unit/currency handling, and quota cost. Sibling differentiation is the only omission.

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 every parameter is already documented; the description only restates the accepted end formats that origin/destination already explain. It adds no default/resolution behavior (e.g., which wins if both origin and origin_lat are supplied) beyond the schema, so 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?

Specific verb+resource: plans a route from origin to destination and returns stations within corridor_km sorted cheapest-first with distance from start. That is far more precise than the title. However, it never distinguishes itself from the very similar sibling find_route_stations, so an agent comparing the two must open both schemas to choose.

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 implied by 'Plan a drive and find where to fill up', and the accepted end formats (place name, 'lat,lon', or lat/lon params) guide invocation. But there is no explicit when-to-use/when-not guidance and no mention of calculate_route or find_route_stations as alternatives, even though they overlap heavily.

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