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

Beyond the annotations (non-readOnly, non-destructive, non-idempotent, closed-world), the description discloses important behavior: it is test mode with no real payment, it renders outcome buttons instead of card inputs, and a signed webhook secret is returned exactly once — a one-time-return trait an agent could otherwise miss. It does not cover expiry behavior or what happens if the checkout is never completed.

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?

Two compact sentences, front-loaded with the core action and scope, then completion and inspection paths. No filler; every clause carries information the agent needs.

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?

With 9 parameters at 0% schema coverage and no output schema, the description carries the full burden but only addresses behavior and completion, not parameter meaning or the shape of the returned checkout/secret. An agent knows what the tool does but not how to fill most of its inputs.

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 0% for 9 parameters, and the description explains essentially none of them. It hints at webhookUrl (signed secret returned once) and at amount/currency via 'no real payment', but name, item, ttlSeconds, successUrl, cancelUrl, and description are left entirely undocumented in both schema and prose.

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: 'Create a public hosted checkout with test outcome buttons and no card inputs', and immediately scopes it as test mode with no real payment. It distinguishes itself from wallet_pay (named as a completion method) and from a real checkout, though it does not explicitly contrast with create_test_paywall.

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 implies usage context (test mode, fake cards, wallet_pay for completion, mock tools for inspection) but never states when to choose this over create_test_paywall or complete_test_checkout. Guidance is implied rather than explicit, with no exclusions.

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