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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses the payment model ($0.005 per call, USDC on Base), which is real behavioral context. However, it never states what validation returns (boolean, structured result, error behavior), which is a notable gap given no output schema.

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, front-loaded sentence that carries the resource, format, and pricing with no wasted words. Efficient, though the trailing pricing parenthetical slightly interrupts the core purpose statement.

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 single-parameter validator the description is nearly complete, but with no output schema it should state what a call returns (valid/invalid, error shape). That omission leaves the agent guessing about the result of the call.

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%, so the single 'value' parameter is already documented as an 11-digit legal-entity national ID. The description only restates the same 11-digit constraint, adding no syntax, formatting, or normalization detail beyond the schema. Baseline 3 is appropriate.

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 resource (Iranian company national ID / شناسه ملی اشخاص حقوقی) and specifies it is 11 digits. This distinguishes it functionally from the individual-ID sibling fa_validateNationalId, though it does not name that sibling explicitly.

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 description gives no when-to-use guidance, no exclusions, and does not point to alternatives. With many near-siblings (fa_validateNationalId, fa_validateEconomicCode, fa_validateBankCard, fa_validateSheba), an agent gets no help deciding when a company national ID applies versus those other validators.

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