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

With no annotations, the description carries the full burden. It does disclose a genuine behavioral trait: 'Auth mode: paid' plus the per-call price and payment rails (x402/MPP), which the agent must handle before calling. Beyond that it says nothing about error behavior on an invalid PAN, rate limits, or whether unknown issuers are returned, leaving real gaps.

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 text is bloated with boilerplate: origin URL/hostname/brand, provider aliases, family key, endpoint, five repeated 'Keyword' lines, aliases that duplicate use cases, and the source description repeated verbatim. The actual purpose is one line buried in noise, so structure is poor and much of the content is 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 simple one-parameter validator with no output schema, the description does convey the operation, input format, and that it reports the issuing bank. Missing are return-shape details (e.g. valid/invalid boolean plus issuer name) and error handling, so it is adequate but not complete.

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 0% for the single 'value' parameter, so the description must compensate. It partially does by stating the expected input is a '16-digit PAN', which tells the agent the format. It adds no syntax details (spaces, dashes, Persian digits) beyond that, so it only partially fills the 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 'Summary'/'Source description' lines state a specific verb+resource: 'Validate an Iranian bank card number (16-digit PAN) with the Luhn checksum and report the issuing bank.' That is clear and distinguishes it from sibling validators like iran_sheba or iran_national_id. However, the signal is buried inside a large metadata dump rather than front-loaded, so it is not a clean 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?

Three 'Use case' lines describe the scenario (validate a card, run Luhn, identify issuer), giving implied context for when to use it. But there is no explicit contrast with siblings (e.g. when to prefer this over iran_sheba) and no exclusions, so guidance stops at implied usage.

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