Create payment

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

Annotations already declare openWorldHint, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds genuine value beyond that: the four concrete frontend handling modes for `checkout` (js_sdk, redirect, form_post, manual) and the obligation to persist orderRef + providerOrderId. It stops short of covering failure modes or how provider errors surface.

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?

Two short sentences, zero filler, front-loaded with the verb+resource and then the return-shape enumeration. Every clause carries actionable information.

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?

With 12 parameters, a nested customer object, an open provider enum, and no output schema, the description does the essential work of explaining the response envelope (`checkout` modes), which is the non-obvious part. Remaining gaps — error behavior, provider-specific requirements beyond the schema's return_url note — are minor because the schema is fairly rich.

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 75% and the schema itself documents amount units, order_ref pattern, notify_url/return_url semantics, and idempotency_key default. The description mentions only `checkout` and providerOrderId persistence and adds no meaning to `provider_options`, `include_raw`, or `metadata` beyond what the schema states, so the baseline 3 applies.

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?

States a specific verb and resource ('Create an order / payment session') and immediately clarifies the return contract via the `checkout` discriminator. The action is unambiguously distinct from the sibling set (verify, refund, get_status, cancel_subscription), so an agent can route here without opening the schema.

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 implies the initiation context and gives an operational instruction ('Persist orderRef + providerOrderId'), but never states when to prefer this over `payments_recommend_gateway` (gateway selection), `payments_mock_complete_payment` (testing), or `payments_create_subscription` (recurring). Usage is implied rather than prescribed.

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