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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, openWorldHint=true, so the safety profile is fully covered. The description adds useful behavioral context about the detail-vs-summary shaping of results, but says nothing about freshness of prices, rate limits, or coverage gaps for unsupported countries.

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?

Front-loads the resource and coverage, then the mode switch. The third sentence largely restates sentence one in colloquial terms; it aids synonym matching but is redundant on strict reading.

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 and the safety profile is fully annotation-covered, so the description only needs to convey scope and the filter/no-filter behavior, which it does. Minor gap: no mention of price staleness or unsupported countries.

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%, including a detailed locale description and country_code semantics, so the schema carries the parameter burden. The description only restates the country_code conditional (detail vs list) and ignores locale entirely, adding little beyond what the schema already says.

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?

States specific verb+resource and enumerates the fuel types (gasoline, diesel, LPG, CNG, E85, kerosene), plus distinguishes the two modes (single country detail vs all-country summary). It never names or contrasts with sibling tools like compare_fuel_prices or find_cheapest_fuel, so an agent must infer the boundary itself.

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?

Gives a clear conditional: pass country_code for one country in detail, omit it for a summary list, and names colloquial synonyms (petrol, autogas/propane) that help query matching. However it offers no guidance against the closely related siblings compare_fuel_prices and find_cheapest_fuel, which is exactly where mis-selection risk is highest.

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