get_fx_rate

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

Beyond the annotations (readOnlyHint, openWorldHint), the description adds valuable behavioral context: pricing, payment method, and a documentation link. This discloses cost and client requirements, which are not in annotations.

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 extremely concise: one clear sentence followed by four bullet points listing price, payment, client, and docs. Every sentence adds unique value with no redundancy.

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?

Given zero parameters, an output schema exists, and annotations cover safety, the description is complete. It explains the tool's purpose, cost, and required client, which suffices for a simple retrieval tool.

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 tool has zero parameters, so the schema covers all (100%). The description adds no parameter info, but as per guidelines, 0 parameters yields a baseline of 4. The description still provides purpose and payment context.

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 'Get current USD/KRW exchange rate' and specifies its use for converting between Korean Won and US Dollar prices. This is a specific verb+resource and distinguishes it from sibling tools that focus on arbitrage, news, sentiment, etc.

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 provides clear context on usage: it costs $0.001 USDC per call, uses x402 micropayment, and lists compatible clients and docs. However, it lacks explicit 'when to use' vs 'when not to use' instructions, though the purpose is inherently specific.

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