validate_iban

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

No annotations are provided, so the description carries full burden. It discloses the tool's read-only nature (validation and enrichment), cost structure, and specific data returned (e.g., issuer_class, SEPA reachability). However, it does not explicitly mention error handling or behavior for invalid IBANs (e.g., whether valid=false is always returned). The description is strong but lacks a minor transparency element.

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 well-structured with clear sections (USE WHEN, PREFER OVER, RETURNS, COST) and front-loaded with the main purpose. It is somewhat verbose but every sentence adds necessary context. It could be slightly more concise without losing clarity.

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 presence of an output schema (mentioned in context), the description appropriately focuses on key return fields (valid, bic_resolved, issuer_class, etc.) without redundant detail. It also covers usage context, cost, and sibling differentiation, making it fully complete for an agent to decide and invoke 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 covers the single 'iban' parameter with a description. The description adds value by clarifying that spaces and lowercase are accepted, providing multiple examples, and explaining the enrichment context. This goes beyond the schema's minimal 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 begins with a clear verb and resource: 'Verify whether a European IBAN is valid AND enrich it with bank, compliance and routing data.' It lists specific use cases (e.g., detecting typos, identifying issuer type) and explicitly distinguishes itself from sibling tools like 'batch_validate_iban' and 'lookup_bic' by highlighting its enrichment capabilities.

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 a dedicated 'USE WHEN' section with concrete scenarios (e.g., user mentions IBAN, asks to verify bank account number, pre-check VoP). It also gives a clear preference over local validation with reasoning (mod-97 only catches typos). Cost information and free tier conditions further guide appropriate usage.

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