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

Goes well beyond the annotations by disclosing preview semantics ('it returns a preview of what would change and a confirmation link') and an out-of-band completion step. The annotation set (readOnlyHint=false, destructiveHint=false) is consistent with a flow that issues a confirmation token but performs no destructive change; no contradiction, though the 'changes nothing' wording sits in mild tension with readOnlyHint=false and could have been reconciled explicitly.

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?

Purpose is front-loaded and the preview/confirmation caveat is valuable, but 'Money is integer minor units (cents)' is dead weight for a tool whose only parameter is an enum with no amounts. That sentence consumes roughly a third of the text without helping an agent call this tool.

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 single-enum, one-required-parameter tool with no output schema, the description usefully states what the call returns (a preview plus confirmation link) and who can finalize the change. Combined with the rich enum documentation, an agent has enough to act; only prerequisite/ordering guidance is thin.

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 100%, and the enum's own description already explains 'own' vs 'hosted', provider coverage, and the fallback behaviour in more detail than the description does. The description adds no parameter meaning — its one parameter-related sentence ('Money is integer minor units (cents)') is irrelevant, since this tool has no monetary parameter.

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+resource: 'Choose which checkout shoppers pay on' — an agent knows this sets the payment checkout mode. It does not differentiate from the nearby sibling settings_checkout_extras, so an agent comparing the two settings_checkout* tools gets no routing help.

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?

Usage is implied by context (configuring checkout) and the description hints at a workflow — the merchant must complete the change on a returned page. But there is no explicit when-to-use vs alternatives guidance, no mention of prerequisites such as provider keys, and no exclusion against settings_checkout_extras.

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