validate_iban

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

With no annotations provided, the description carries the full burden, and it delivers: it discloses the 77-country scope, the ISO 7064 MOD-97-10 checksum, the pure-math/no-external-API behavior, and the exact return keys. This gives an agent a reliable picture of what will happen when invoked.

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 compact and well-structured with a one-sentence purpose statement, a short behavioral note, an Args section, and a Returns section. Every sentence adds value, and the most important information is front-loaded.

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 simple single-parameter schema and no output schema, the description is complete: it explains the input format, what validation is performed, and what the response contains. An agent has everything needed to select and invoke this tool correctly.

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 schema provides zero description coverage, but the description fully compensates by documenting the single iban parameter, including the acceptable format ('optional spaces') and a concrete example. Since there is only one parameter, this is complete parameter guidance.

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 opens with a clear verb and resource: 'Validate an IBAN (International Bank Account Number).' It then states exactly what validation covers (format, length, checksum) and stands apart from sibling validators like validate_vat and validate_credit_card by naming IBAN explicitly.

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 for when to call the tool: whenever an IBAN needs syntactic and checksum validation. It also adds a differentiating trait, 'No external API — pure math,' which signals suitability for offline or no-fee validation. It does not explicitly list alternatives, but the resource type makes the intended use obvious.

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