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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds useful context about the returned data fields, including SEPA membership, currency, regex, and an example IBAN, but it does not disclose error behavior for unsupported countries or any other operational traits.

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 a single dense sentence that front-loads the resource and enumerates the returned fields without wasted words. It could be slightly clearer with an explicit action verb, but it is appropriately sized for a lookup tool.

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 simple one-parameter lookup with no output schema, the description compensates by listing the key fields the tool returns. It does not mention behavior for unknown or unsupported country inputs, but otherwise gives enough context to call the 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?

Schema description coverage is 100%, and the single parameter is documented as 'Country name or ISO code.' The description adds no additional syntax, format, or constraint details beyond what the schema already 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 makes clear that the tool provides country-specific IBAN format metadata, listing the exact fields returned such as length, structure, SEPA membership, currency, and regex. It is specific about the resource, but it does not explicitly name a verb or distinguish itself from siblings like validate_ibans or calculate_iban.

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?

There is no explicit guidance on when to use this tool versus alternatives such as calculate_iban, validate_ibans, or generate_test_ibans. The implied use case is looking up a country's IBAN format, but no conditions, exclusions, or sibling routing are stated.

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