List available payment methods

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

Annotations already cover readOnlyHint and destructiveHint; the description adds useful behavioral context beyond them: cart must be non-empty, a mobile API token must be loaded, and if not, the auth_start/user-sign-in/auth_exchange flow must run first. It does not describe error behavior or result shape, but that is a minor gap for a read-only list.

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 dense but every sentence carries necessary information: what it lists, when to call it, what it returns, prerequisites, and the auth fallback. The main purpose is front-loaded and no filler is present.

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 one-parameter, read-only listing tool, this is complete: it states prerequisites, sequencing, the intended user-facing purpose, and the downstream consumption of payment_id by web_place_order or mobile checkout. Nothing needed to decide to call it is missing.

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 single parameter is fully documented in the schema, including its source (delivery_options) and optionality ('Omit for the default set'). The description reinforces the delivery_options relationship but adds no new parameter semantics beyond the schema, so the baseline of 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?

The description opens with a specific verb and resource: 'List the payment-method groups available for the current Alza account cart'. It also explains the purpose of the result (show payment choices, obtain payment_id) and situates the call between delivery_options and order submission, making it easy to distinguish from sibling tools.

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?

It gives explicit sequencing: use after delivery_options and before order submission, and lists the exact requirements (non-empty cart, loaded mobile API token) with a fallback auth flow. It does not explicitly name when-not-to-use alternatives such as after-order payment tools, which keeps it just 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.