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

With no annotations, the description carries the full burden, and it does disclose two useful traits: the mod-97 verification method and the cost model ($0.005 per call, USDC on Base). However, it says nothing about what a call returns (boolean vs. structured result) or how invalid input is reported, which is a meaningful gap for a validator.

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?

One front-loaded sentence with the core purpose first and pricing appended parenthetically. No filler, nothing redundant.

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, no-nesting validation tool the description is nearly sufficient, and the cost disclosure is a bonus. The only shortfall is that, with no output schema, the return value (valid/invalid signal or error shape) is never described.

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 coverage is 100% and the single 'value' parameter is documented as 'IR + 24 digits'. The description's 'Iranian IBAN/Sheba' framing adds meaning but no format or syntax detail beyond the schema, so the baseline of 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?

States a specific verb (Validate) and a precise resource (Iranian IBAN/Sheba / شبا) and even names the algorithm (mod-97 check), which cleanly separates it from the other fa_validate* siblings like fa_validateBankCard or fa_validateNationalId.

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?

The tool's role as a Sheba validator is implied clearly, but there is no explicit when-to-use guidance, no mention of prerequisites, and no routing to or from the sibling validate tools. Adequate but leaves the agent to infer context.

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