Create Payment Method

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

The description adds a meaningful warning to 'handle card data with care', indicative of sensitive data handling. However, it does not disclose side effects beyond creation (e.g., whether it validates, charges, or stores the card). The openWorldHint annotation is not explained, so the description provides only modest behavioral context.

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 description is two concise sentences, front-loading the core purpose and including only a brief necessary caution. No wasted words or redundant schema repetition.

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 tool with 3 parameters, nested objects, and no output schema, the description is minimal but adequate for basic invocation. It explains the role in the payment workflow ('attach to a payment intent') and warns about sensitive data, but lacks information on return values, error behavior, or how the payment method is ultimately attached.

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?

The input schema already provides descriptions for all parameters (100% coverage), so the description does not need to repeat them. The description mentions 'card' as an example, which aligns with the schema's 'details' field, but adds no additional parameter-level semantics.

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 action ('Create a payment method') and provides an example ('e.g. a card') with a purpose ('to attach to a payment intent'). This distinguishes it from general creation tools, though it does not explicitly contrast with sibling tools like create_source, leaving some ambiguity.

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 phrase 'to attach to a payment intent' gives clear context for when this tool should be used, implying the intended workflow. However, it does not explicitly mention alternatives or when not to use it, so it stops short of full guidance.

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