ucp_checkout_create

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

No annotations are provided, so the description must disclose behavioral traits. While it explains inputs and outputs, it omits details like side effects (does this create a persistent session?), required authentication, idempotency, or error conditions. The fact that it 'creates' implies mutation, but no further safety or state info.

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 well-structured with 'Args' and 'Returns' sections, each parameter on a separate line. It is concise enough—5 parameters described in a few sentences—but could be slightly more compact by omitting the explicit 'Args' label if not needed.

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 5 parameters, no annotations, and presence of an output schema, the description covers all inputs and defines the return structure. However, it lacks mention of authentication, error handling, or prerequisites (e.g., merchant must be discoverable via ucp_discover). Enough for basic use but not exhaustive.

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 has 0% description coverage, but the description fully compensates by explaining each parameter's meaning, including the structure of 'items' (list with 'id' and 'quantity') and default for 'currency'. All 5 parameters are clearly defined, and the return dictionary is detailed.

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 new checkout session') and the resource ('UCP merchant'). It provides specific parameter explanations and return values, but does not explicitly differentiate from sibling tools like ucp_checkout_complete or ucp_checkout_update.

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?

No guidance on when to use this tool versus alternatives. The description does not mention prerequisites, typical workflow (e.g., start a checkout before completing it), or scenarios where another sibling would be appropriate. Sibling tool names are listed but without context.

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