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

The description discloses the x402 micropayment requirement and the specific output components (amount after rail fees, variance in dollars, stability overlay, execution window), which add behavioral context beyond the readOnlyHint annotation. There is no contradiction with annotations; the read-only nature is consistent with a quote tool.

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 three focused sentences that front-load the tool's purpose, then detail the output, and finally answer the user's implicit question with a requirement. Every sentence adds value; no filler or 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 the complexity of cross-border settlement cost and the presence of an output schema, the description is sufficiently complete. It covers the tool's purpose, the key output dimensions, and the payment prerequisite, while the schema and annotations handle parameters and safety.

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 has 100% description coverage, so the description does not need to explain parameters; the baseline is 3. The description adds no parameter-specific detail beyond the schema, though it clarifies that 'amount' refers to the amount sent in the example question.

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 'All-in settlement cost quote for cross-border payments' and details the output as exact amount received, FX cost variance, stability overlay, and execution window. This specific verb+resource phrasing distinguishes it from sibling tools like fx.rate (simple rate lookup) and fx.corridors (corridor data).

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 implies use when a CFO-grade, all-in cost certainty quote is needed for cross-border payments, providing clear context. However, it does not explicitly state when not to use it or name alternative tools (e.g., settlement.quote) for comparison, so it lacks explicit exclusions.

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