iban_check

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

With no annotations provided, the description carries the full burden. It discloses core behaviors: validates structure/length/checksum, extracts bank identifier, does not verify account existence, and costs 1 API unit. It also includes a limitation. However, it does not describe the response format or error handling, which would enhance transparency further.

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 two sentences long, front-loaded with the primary action, and includes only essential information (validation details, extraction, limitation, cost). Every sentence serves a purpose, with no filler or repetition.

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 tool's simplicity (one parameter, no output schema), the description covers the main aspects: what is validated, what is extracted, the key limitation, and the cost. However, it does not specify the return format (e.g., boolean, object with details), which would be useful since there is no output schema. Still, it is largely complete for a validation 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?

The schema coverage is 100%, with the parameter 'iban' described as 'The IBAN to validate; spaces are allowed'. The description does not add new parameter-level details beyond rephrasing that it validates an IBAN. Since the schema already explains the parameter, the baseline of 3 applies.

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 uses a specific verb ('validate') and resource ('IBAN'), detailing exactly what is validated (country structure, length, MOD-97 checksum) and what is extracted (public bank identifier). It clearly distinguishes itself from sibling tools like email_check and vat_check by focusing on IBAN-specific functionality.

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 clearly implies when to use this tool (to validate an IBAN) and explicitly states a limitation ('Does not verify that the account exists or who owns it'), guiding the user away from using it for that purpose. However, it does not name alternative tools for account verification, so it lacks explicit alternatives.

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