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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is covered. The description usefully discloses the validation standard (mod-97 plus KZ structural rules) and cost, but does not say what an invalid input produces (boolean vs error message), leaving the outcome shape implicit.

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?

A single short sentence with the verb and resource front-loaded and the algorithm in parentheses; the 'Free.' tag is terse and non-disruptive. Nothing here wastes the agent's attention.

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 validator with full schema coverage and annotations covering safety, the definition is nearly sufficient. The only gap is the return-value semantics, which an output schema would normally cover but does not exist here.

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 schema already spells out the 20-character KZ format with spaces allowed and an example. The description adds no parameter meaning beyond that, so the baseline 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 names a specific verb (validate) and resource (Kazakhstan IBAN), and adds the underlying algorithm (ISO 7064 mod-97 + KZ structure), so the purpose is unmistakable. It doesn't explicitly distinguish itself from the sibling validate_iin, but the different resource makes the split inferable.

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 statement of when to use this tool versus alternatives, nor any prerequisites or exclusions. The only added clause is 'Free.', which says nothing about invocation context.

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