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

The description adds substantial context beyond the read-only, idempotent annotations: it explains the validation rules, the data_confidence levels, the bundled registry limitation, and the important disclaimer that structural validation is not proof of issuance or ownership. These details materially improve safe interpretation of the result.

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 definition is front-loaded with the core action and stays focused, but the response-field enumeration is somewhat dense given that an output schema exists. The disclaimer and confidence semantics justify most of the length.

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?

For a single-parameter validation tool with annotations and an output schema, the description is complete enough for correct invocation and result interpretation. It covers validation scope, returned data, confidence semantics, provenance, and the structural-only caveat.

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 single iban parameter is already documented in the schema. The description gives an example but does not add meaningful syntax or semantic detail beyond what the schema provides.

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 names a specific verb and resource and clarifies the validation scope: ISO 13616 length, mod-97, and national BBAN rules. It also lists the returned data. It does not explicitly distinguish itself from siblings such as validate_identifier or validate_bic, which keeps it below a 5.

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?

Usage is implied by the IBAN-specific scope and the example, but the description does not state when to choose this tool over validate_identifier or validate_bic. No exclusions or routing guidance are provided.

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