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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds no new behavioral details beyond the estimation function, which aligns with these hints. It does not disclose anything about rate limits, authentication, or response structure, but this is acceptable given the annotation coverage.

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 a single, efficient sentence that front-loads the primary purpose and lists the key cost components without filler. It communicates the tool's value in one breath, making it easy for an agent to parse quickly.

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 comprehensive schema (all 8 parameters documented) and annotations covering safety, the description adequately conveys what the tool does and what it returns (estimates of rates, fees, amount, and limits). The absence of an output schema is mitigated by the description's enumeration of the output contents. It could be more explicit about the exact response structure, but 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 description coverage is 100% with detailed descriptions for every parameter, so the schema carries the semantic weight. The description adds minor value by giving examples of the network enum (ACH, SEPA, EFT) and tying them to the concept of 'rails', but this is redundant with the schema's 'Fiat payout rail / bank method' description.

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 states a clear, specific purpose: 'Estimate exchange rates, processing fees, amount received, and corridor limits for a bank payout before sending money.' It names the resource (bank payout quote) and distinguishes it from sibling tools that handle portfolios, transactions, or sync, making its role unambiguous.

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?

It explicitly advises using the tool 'before sending money' and recommends it for comparing rails like ACH, SEPA, EFT, etc. There are no exclusion criteria or mention of alternative tools, but since no sibling tool provides quote functionality, the guidance is sufficient. A missing 'when not to use' clause prevents a 5.

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