Start subscription checkout

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

The annotations only provide coarse flags, so the description carries most of the behavioral burden. It adds valuable context: the human must open the URL, webhook latency exists, checkout is production-only, and login is required. It does not, however, surface the paid-operation confirmation-token requirement or the dry-run/apply sequencing, which are important behavioral traits beyond the raw schema.

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?

Five short sentences, each earning its place: the core action, the user step, the post-payment polling behavior, the environment restriction, and the auth requirement. The most important information is front-loaded.

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?

Paired with the complete schema and output schema, the description gives the agent enough to act. However, the two-phase dry-run/apply flow and the confirmation-token requirement for paid operations are only present in the schema, not in the operational narrative, leaving a real gap for a non-trivial paid checkout flow.

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%, and the schema already explains mode, priceId, returnUrl, planDigest, and confirmationToken. The description only indirectly references the plan via 'chosen plan' and adds no real parameter-level meaning, so it stays at the baseline.

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 states a specific action and resource: 'Create a Stripe Checkout URL for the chosen plan.' This clearly separates it from sibling tools like list_subscription_plans, get_onboarding_status, and auth tools, and it even identifies the follow-up polling step.

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 when-to-use context: give the URL to the user because card entry cannot be automated, poll get_onboarding_status after payment, and avoid this tool in sandbox because a subscription is not required there. It also names the auth prerequisite.

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