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

Annotations say non-read-only, non-idempotent, non-destructive, open-world. The description adds real behavioral context: it records acceptance, returns a Stripe payment page, and nothing is charged until the shopper pays. It also discloses refusal conditions (expired quote, changed order). Missing explicit mention of idempotency/duplicate-call behavior, so not a 5.

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?

Four short sentences, each earning its place: precondition, action/return, payment reassurance, failure handling. All front-loaded with no filler.

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-param, no-output-schema tool, it covers everything an agent needs: when to call, what it returns, that no money moves yet, and what to do on refusal. Complexity is low and the description matches it.

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?

Only one parameter, checkout_token, and schema coverage is 100%, so the schema already documents it. The description names related fields (checkout_url, quote_expires_at) but doesn't add syntax or semantics beyond the schema.

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 (confirms the checkout, records acceptance) and clearly differentiates from the sibling create_checkout by defining itself as the post-review confirmation step that yields a payment link.

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?

Explicit preconditions: 'Call only after the shopper has seen and accepted the create_checkout review.' Also gives a fallback path ('then call create_checkout again') when the quote expired or details changed, so the agent knows when this tool is and isn't the right call.

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