Initiate checkout for a cart. Provide cart_token from add_to_cart and a billing email. Returns a payment_token required to complete the purchase.
| Name | Required | Description | Default |
|---|---|---|---|
| Yes | |||
| cart_token | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses the action (initiating checkout), the prerequisite (cart_token from add_to_cart), the need for a billing email, and the output (payment_token). This provides some behavioral context, but it does not mention potential side effects (e.g., payment holds, cart state changes) or permission requirements, so it is only minimally transparent.
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 sentences, front-loaded with the primary action. Every word contributes: the first sentence states the purpose, the second explains inputs and output. There is no redundancy or filler, making it appropriately concise.
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?
The tool is simple (two string parameters, no nested objects, output schema present). The description covers the essential flow: inputs, source of cart_token, and the returned payment_token. It could mention error conditions or explicitly connect to confirm_payment, but given the low complexity and existing output schema, it is largely 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?
The input schema provides only field names and types with no descriptions. The description compensates by adding semantics: cart_token is sourced from add_to_cart, and email is specifically a billing email. This makes both parameters meaningful and clarifies their purpose, though it stops short of specifying formats or validation rules.
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 initiates checkout for a cart, specifies the required inputs (cart_token from add_to_cart and a billing email), and mentions the output (payment_token). This distinct verb+resource+flow makes it easy to differentiate from sibling tools like add_to_cart, confirm_payment, get_product, and search_products.
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 contextual guidance by instructing to provide the cart_token from add_to_cart, implying it should be used after cart building. It also notes the payment_token is required to complete the purchase, indicating a follow-up step. However, it does not explicitly name alternatives or say when not to use this tool, so it falls short of a 5.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Each tool has a distinct role: product discovery (search_products, get_product), cart management (add_to_cart), and payment processing (checkout, confirm_payment). The sequential flow is clear and there is no overlap between tools.
Most tools follow a consistent lowercase verb_noun pattern (add_to_cart, confirm_payment, get_product, search_products). 'checkout' deviates slightly as a single verb, but it is still clear and follows the same overall style.
With 5 tools, the server is well-scoped for a simple purchase workflow. Each tool is necessary for the core flow of searching, viewing, adding to cart, and completing a purchase.
The purchase lifecycle is covered end-to-end: search, retrieve details, add to cart, checkout, and confirm payment. Minor gaps exist such as no update/remove cart functionality, but these do not block the primary workflow.