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

Adds real context beyond the annotations: it discloses the deterministic checksum method, states the limits of what a pass/fail means (cannot confirm the recipient or prevent reversals), and notes it returns a signed XDR-1 receipt. Annotations already cover read-only/idempotent/OpenWorld, so this is a solid supplement.

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?

Two tightly packed sentences, front-loaded with the method and followed by the caveat. Zero filler; every clause carries information an agent needs.

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?

An output schema exists, so return values need not be explained, and the description covers method, scope, and limitations. The only real gap is the unaddressed duplicate/alias parameters with zero required fields, which an agent must resolve from the schema alone.

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%, so the schema already documents both parameters. The description adds nothing about the aliasing between 'routing' and 'aba_routing' or which to supply, leaving that entirely to the schema — baseline 3.

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 (validate), a specific resource (US ABA routing number), and even the exact algorithm used ((3,7,1)-weight mod-10 Fedwire/ACH checksum). This clearly separates it from siblings like swift_bic_check, iban_check, or uscc_check.

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 an explicit usage condition — catch mistyped routing numbers before payment — plus scope exclusions (does not prevent transfer reversals, does not establish the recipient). It stops short of naming which sibling to use instead for identity or reversal concerns, so routing is implied rather than prescribed.

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