qm_data_fx

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

With no annotations provided, this description carries the full behavioral burden and does so thoroughly: it discloses pricing ($0.01 USDC on Base via x402), the two-phase payment dance, the exact call sequence, and the safety guarantees ('never pays, never touches private keys, never holds funds'). This is far beyond what the schema alone conveys.

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 purpose in the first clause, then payment mechanics, then safety, then resale terms — a logical sequence. Slightly conversational ('the data comes back in the tool result') and the resale notice is a nice-to-have rather than essential, but overall efficient.

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 paid atomic data tool with no output schema and no annotations, the description covers everything an agent needs: what it does, cost, the two-phase invocation protocol, safe-handling guarantees, and permission to resell. Nothing critical is missing.

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% — all four parameters are fully documented in the input schema itself, including the base64 x402 payload format and the omit-on-first-call semantics. The description adds ordering/explanatory context but does not add field-level meaning beyond the schema, so the 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?

States a specific verb+resource ('Fiat currency conversion') and enumerates concrete use cases (pricing, payouts, multi-currency accounting). Distinguishes itself from the qm_data_* siblings (crypto, country, etc.) by being specifically fiat conversion at reference rates.

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 strong context: 'pricing, payouts, or multi-currency accounting' tells when it applies, and the two-phase payment flow explicitly instructs how to call it. However, it does not explicitly say when NOT to use it vs. e.g. qm_data_crypto for crypto-rate work, leaving that inference to the agent.

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