Pay Saved Card

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 includes a safety note about confirmSubmitPayment being required for live execution, which adds transparency. However, it does not disclose side effects, auth requirements, or error behavior.

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 extremely concise at two sentences, front-loaded with the core action, and contains no unnecessary words. Every sentence serves a purpose.

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 7 parameters (one required) and no output schema, the description is insufficient. It omits details on return values, error handling, polling behavior (pollCount), wallet inclusion (includeWallet), and device session requirements, leaving the agent underinformed.

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 only 14% (only confirmSubmitPayment has a description). The description helps with cardIndex and cardId by referencing ninja_pending_payment_methods, but leaves cvv, pollCount, includeWallet, and deviceSessionId unexplained. It adds some value but does not compensate for low coverage.

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's purpose: 'Pay the saved pending checkout with a saved card.' It specifies using cardIndex from ninja_pending_payment_methods or providing cardId, which differentiates it from siblings like ninja_pay_wallet and ninja_initiate_stc_pay.

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 gives guidance on how to identify the card (via cardIndex or cardId) but does not explicitly state when to use this tool versus other payment methods or when not to use it. The usage context is implied but not contrasted with alternatives.

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