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

With only weak annotations (readOnlyHint=false, idempotentHint=false), the description carries the burden and excels. It discloses the two-phase confirmation model, that execution returns checkoutUrl and expiresAt, and that the balance credit is not immediate and must be polled for. This goes well beyond what annotations provide.

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 efficient, front-loading the purpose and then walking through the required follow-up actions in a logical order. Every clause adds necessary behavioral or workflow information, with no filler or repeated schema content.

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 two-phase mutation tool with no output schema, the description covers the essential flow well: actionId, confirmation, checkoutUrl, expiresAt, and polling. The only minor gap is a slight ambiguity around 'present the summary to the user'—it does not specify where that summary content comes from, but the overall workflow is still actionable.

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 description coverage is 100%, so the schema already documents amount, currency, and sessionKey thoroughly. The description does not add parameter-level details beyond what the schema states. Baseline 3 is appropriate.

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: 'Stage a Stripe checkout session to add funds to the account balance.' This clearly differentiates it from payment-related siblings like payInvoice (paying an existing invoice) and getPaymentTransactions (reading transactions). An agent can immediately tell what the tool accomplishes.

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 gives clear process guidance: requires authentication, returns an actionId, must be confirmed via executeConfirmedAction, and should be followed by polling getPaymentTransactions. It does not explicitly contrast with alternatives like payInvoice or previewPaymentFees, but the flow and purpose are clear enough that an agent can decide when to invoke it.

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