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

The description discloses the cost of $0.001 USDC via x402, which is a behavioral trait not covered by annotations (none provided). However, it does not mention failure modes, caching, or output format, leaving some transparency gaps.

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 concise and front-loaded: it states the purpose in the first clause and the cost in the second. No unnecessary words or repetition.

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 simple read-only tool with one optional parameter, the description covers the essential context: what data is returned, from where, and the cost. It does not describe the output structure, but this is not critical given the simplicity and lack of an 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?

The input schema fully documents the optional 'product' parameter with its enumerated values (mogas, gasoil, lpg), so schema coverage is 100%. The description adds no extra meaning beyond the schema, which is acceptable but not above baseline.

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 clearly states the tool retrieves petroleum retail prices from STC Mauritius. The verb 'Get' is specific and the resource is well-defined, distinguishing it from sibling tools like forex_rates or weather.

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 gives clear context: use this tool when you need petroleum retail prices from STC Mauritius. It does not explicitly mention alternatives or exclusions, but the specificity of the source implies the appropriate use case.

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