validate_iban

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

Describes validation logic (country, length, checksum) and return values (country, check digits, BBAN). No annotations provided, so description carries full burden; it is thorough but does not mention external dependencies or permissions.

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 sentences, no wasted words, front-loaded with directive 'USE THIS'. Every sentence contributes meaning.

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?

With no output schema, the description adequately explains what is returned. Single parameter case; no gaps. Complete for this simple 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?

Schema already describes the 'iban' parameter; the description adds that spaces are ignored, providing additional clarity beyond the schema. With 100% schema coverage, this extra detail is valuable.

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?

Description clearly states it validates IBANs, specifies what is checked (country, length, checksum), and explicitly distinguishes from sibling tools that validate cards, ISBNs, and VINs.

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?

Explicitly instructs when to call ('whenever a user supplies a bank account for a payment, payout or invoice'). Does not mention when not to use or alternatives, but siblings are clearly different domains.

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