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

No annotations are provided, so the description carries the full burden. It does disclose genuinely useful operational context — the pay-per-call price and settlement chain ($0.005, USDC on Base) — but it never says whether this is a pure read-only check or what a pass/fail verdict looks like.

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 line: identifier, format constraint, localized name, then cost. No filler, nothing that could be dropped without losing information.

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?

With no annotations and no output schema, the description should at minimum indicate the shape of the result (boolean vs. object with reason/region). A validator's entire value is its verdict, and that is left completely undocumented.

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% for the single 'value' parameter, so baseline is 3. The description's '10 digits' constraint and Persian term merely restate what the schema already specifies, adding no syntax or format detail beyond it.

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) plus a precise resource (Iranian postal code, 10 digits) with the local term کد پستی. Against the fa_* sibling set, the resource noun alone separates it cleanly from fa_validateNationalId, fa_validateSheba, etc.

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 says nothing about when to reach for this versus the other validators, nor any precondition (e.g. input must already be normalized digits). Usage is only inferable from the resource name.

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