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

Beyond the readOnly/idempotent annotations, the description discloses critical behavior: non-custodial funds, seller OFAC screening, gateway fee formula, charging only on seller 2xx responses, prepaid-credit requirements, and API-key header usage. These details materially affect whether and how an agent should use the tool.

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 main purpose and critical payment behavior are front-loaded, but the description is dense and includes lengthy credit-pack and referral-program details that are not essential for selecting or invoking this tool. It would benefit from trimming operational/marketing details into referenced docs.

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?

Given the tool has an output schema, the description does not need to fully explain return values, yet it still summarizes gatewayUrl, price, and fee. It also covers the non-custodial model, prepaid credits, API-key requirement, and charging conditions, leaving little ambiguity for invocation.

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 schema already documents both url and method. The description adds context about the seller endpoint being prechecked, but does not add syntax or semantics for the method parameter beyond what the schema provides.

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 description clearly states the tool prechecks an x402 seller and returns the gatewayUrl, price, and gateway fee. However, its overlap with the sibling x402_precheck is not explicitly addressed, so an agent may not immediately see why it should choose this tool over the raw precheck.

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?

It gives clear usage context: call this before paying an x402 seller through the MoneyTools Pay Gateway, then call the returned gatewayUrl with X-API-Key. It does not explicitly exclude alternatives or explain when to use x402_precheck or x402_recommend instead.

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