fuel_nearby_stations

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds ordering behavior (nearest first) and field scope. However, it doesn't disclose details like pagination limits behavior or what happens when max_results/radius are exceeded, though the schema constraints (min/max) partially cover this. With strong annotation coverage, the description's additions are sufficient but not rich.

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?

Single concise sentence that efficiently enumerates what's returned (prices, brand, amenities, flags) plus ordering (nearest first). Zero waste, front-loaded with the action. Every word 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?

With a good output schema present, an output_format annotation available, and strong safety annotations (readOnly, idempotent, non-destructive), the description doesn't need to explain return values. It covers the core result content and ordering. For a list-type read tool with output schema available, this is reasonably complete, though slightly more sibling differentiation would push it to 5.

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 only 33% — only the location parameter has a description in the schema ('UK postcode, outcode or lat,lon'). The description itself doesn't elaborate on max_results or radius_miles semantics, though the schema provides min/max/default values for those. Since location is the only required param and is well-described in the schema, the description adds minimal value but the critical param is covered.

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?

Clearly states the tool lists forecourts near a location (nearest first) with specific attributes included: fuel prices, brand, amenities, and motorway/supermarket flags. It also notes ordering (nearest first). This distinguishes it from siblings like fuel_find_cheapest (which focuses on cheapest) and fuel_area_summary (area aggregation). Specific verb+resource+scope.

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 implies it's for finding nearby stations with full detail, but doesn't explicitly state when to use it vs fuel_find_cheapest or fuel_area_summary. There's no when-not guidance or named alternatives. The 'nearest first' ordering and comprehensive field listing give some usage context, but explicit differentiation from siblings is absent.

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