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

With no annotations, the description carries the full transparency burden; it explicitly states 'Stateless validator: records no decision and leaves no dashboard timeline trace,' disclosing the absence of side effects, and scopes behavior to 71 countries.

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?

Single information-dense sentence; front-loaded with action and object, with scope and side-effect disclosure in a second clause. No wasted words.

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?

Covers purpose, algorithm, country scope, and side-effect profile for a simple one-parameter validator. It stops short of specifying return-value shape, but the absence of an output schema and low complexity keep this from being a major gap.

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 one parameter is only a bare string named 'iban'; the description adds no format examples, normalization rules, or accepted input constraints. Since schema coverage is 0%, the description fails to compensate for this gap.

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 opens with a specific verb and object ('Validate an IBAN') and adds technical scope ('ISO 7064 mod-97 check digit; supports 71 countries'), making it clearly distinct from sibling validators like cpf_validate or sin_validate.

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?

It clearly implies IBAN validation is the use case, but it does not explicitly contrast with other validators, state when not to use it, or mention prerequisites. Clear context is present, though exclusions are absent.

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