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

With no annotations, the description carries the full burden of behavioral disclosure. It states 'offline', which is a meaningful behavioral trait (no network dependence), and specifies the validation components (checksum + country/length). However, it does not disclose whether the operation is read-only, what it returns, or any other side effects, so it earns a 3.

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 extremely concise, consisting of a single sentence that front-loads the core action ('IBAN Validate') and adds relevant detail efficiently. No wasted words, but it is minimal to the point of lacking some helpful context, preventing a 5.

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?

The tool is simple (one optional parameter, no required fields) and has an output schema, but the description is too minimal to be complete. It does not explicitly state the input semantics, expected output behavior, or any prerequisites. Given the lack of annotations and the description's brevity, it is not enough for an agent to fully understand the tool's behavior, earning a 2.

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 has one parameter 'q' with 0% description coverage, and the description does not clarify what 'q' represents or its expected format. Although the tool name suggests 'q' is the IBAN string, this is not stated explicitly, so the description fails to compensate for the schema's lack of semantic detail. Score 2.

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' with the resource 'IBAN' and adds technical detail: 'ISO 13616 checksum + country/length (offline)'. This clearly indicates the tool's purpose. It does not explicitly distinguish from sibling validation tools, but the name alone is unambiguous, so it earns a 4 rather than 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?

No guidance is provided on when to use this tool versus alternative validation tools (e.g., checksum, luhn, isbn). The only usage hint is 'offline', which implies it can be used without network, but there is no explicit when-to-use or when-not-to-use guidance, earning a 2.

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