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

Annotations already indicate non-read-only, idempotent, and destructive behavior. The description adds 'Requires authentication' and the prerequisite that the platform must support ACP and have an SPT, providing useful context beyond annotations. It doesn't explicitly state the irreversible charge, but the annotations signal a write operation.

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 three sentences: the first states the purpose, the second gives a condition, and the third provides an alternative. Every sentence earns its place without redundancy or fluff, and it is front-loaded with the core action.

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 tool's complexity, the presence of an output schema, and sibling tools, the description covers purpose, conditions, alternatives, and authentication requirement. It explicitly references checkout_create and checkout_status, integrating it well into the larger workflow. No critical information 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?

Schema descriptions cover all three parameters at 100%, so the baseline is 3. The description adds value by explaining that shared_payment_token is an SPT from the client platform and referencing payment_url from checkout_create as the alternative when ACP isn't supported, enriching understanding of the token 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?

The description opens with 'Complete payment using Stripe ACP (Shared Payment Token),' which is a specific verb+resource and clearly distinguishes this tool from checkout_create (which creates the session) and checkout_status (which polls). It explicitly states the ACP flow, making its purpose unambiguous.

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 says 'Only use this if your platform supports Stripe Agentic Commerce Protocol and can provision an SPT.' Then it explicitly says, 'If your platform does NOT support ACP, use the payment_url from checkout_create instead, then poll checkout_status.' This provides explicit when-to-use, when-not-to-use, and a direct alternative.

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