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

With no annotations, the description must carry the load, and it does disclose operational traits beyond the schema: auth mode is 'paid' and each call costs $0.005 via x402/MPP on Base or Tempo. That is genuinely useful cost/auth context rarely found in descriptions. It still does not say what happens at numeric limits or whether the operation is purely deterministic, which keeps it below a 5.

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 payload is dominated by SEO/registry metadata (origin URL, hostname, brand, family key, endpoint, five keyword lines) and the Summary is duplicated verbatim under 'Source description'. The actual purpose is buried mid-block rather than front-loaded, so much of the text does not earn its place.

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 one-parameter pure text transformation with no output schema, the description supplies the example output, use cases, and pricing/auth — enough for an agent to call it correctly. The remaining gaps (numeric bounds, error behavior) are minor for a deterministic formatting utility.

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?

One parameter with 0% schema description coverage, so the description has to compensate and only partially does: the example conveys the intended numeric input, but there is no guidance on integer vs decimal, negatives, rounding, or an upper bound (relevant for very large amounts). Marginal value over the type-only schema.

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 states a specific verb and resource ('Spell a number out in Persian words') with a concrete input/output example (125000 -> "صد و بیست و پنج هزار"), so the transformation is unambiguous. However, it never differentiates itself from the near-identical sibling `iran_amount_to_words`, leaving the agent to guess which one applies to cheques/invoices.

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 cases are listed (cheque, invoice, contract), which gives implied context for when to call it. But there are no when-not conditions and no mention of the obvious alternative tool (`iran_amount_to_words` or `rial_toman_convert`), so routing guidance is incomplete.

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