Live currency convert (paid $0.001)

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

Discloses the paid nature ($0.001), cached feed, keyless ECB source, informational-only caveat, and the 402 challenge / x_payment flow. This is extensive behavioral transparency beyond annotations (which are absent).

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?

Dense yet compact: three sentences communicate cost, source, use case, payment flow, and argument list. Front-loaded with the PAID flag and 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?

Despite no output schema or annotations, the description covers price, data source, caching, limitations, and payment mechanics. The result (converted amount) is implied and sufficient for a simple converter.

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 covers all parameters with 100% coverage. The description briefly mentions amount, from, to (ISO-4217) and x_payment behavior, but this largely mirrors the schema, adding little new semantic value.

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 converts amounts between currencies using reference/mid-market rates from the ECB. The verb 'Convert' plus the specific resource (currencies) differentiates it from generic siblings like 'convert'.

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?

Provides clear context: it's for informational reference rates, not dealable quotes, and explains the x402 payment flow. However, it doesn't explicitly mention when to use this tool over a sibling like 'convert'.

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