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

Annotations already disclose openWorldHint=true, idempotentHint=true, destructiveHint=false, and readOnlyHint=false. The description adds genuinely useful context beyond those flags: calling it does not charge a card, and payment is a prerequisite to queue entry. It does not explain what happens if the test is already paid or what side effects creating a checkout session has.

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?

Three short sentences with zero filler, led by the return value and followed by the precondition and the reassurance about charging. Every sentence earns its place.

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 no output schema, the description correctly states what is returned (a Checkout URL) and the payment/queue precondition, and it clarifies there is no immediate charge. It is nearly complete for a single-parameter tool, missing only auth requirements and the already-paid case.

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?

There is one parameter with 0% schema description coverage, so the description must carry the burden and largely fails to. 'Your unpaid test' only loosely implies test_id refers to the test identifier, with no format, source, or expected value given.

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 names a specific verb (get) and resource (Stripe Checkout URL) scoped to 'your unpaid test,' so it is not a tautology of the name. It is distinguishable from siblings like get_test and request_test by resource, though it never names a sibling explicitly, which keeps it just short of a 5.

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 a clear precondition for use: the test must be unpaid and the account owner or authorized payer must complete payment before the test enters the queue. It offers no explicit when-not or named alternative among siblings, so it stops at clear context rather than full routing guidance.

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