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

Annotations already declare idempotentHint=true and destructiveHint=false, but the description goes well beyond them: it explains key binding ('bound to the first idempotencyKey used'), the do-not-switch-keys rule, and replay semantics ('Replaying after success returns the existing unpaid checkout and link... without creating another Stripe session'). This is exactly the behavioral protocol an agent needs to avoid duplicate Stripe sessions.

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 tight sentences with zero filler. The precondition is front-loaded, and the remaining content is dense idempotency guidance that directly affects correct invocation.

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?

Covers the critical workflow (approval, prepared confirmation, idempotent retry, replay behavior) and even hints at the return ('the existing unpaid checkout and link') despite no output schema. Minor gaps remain: the 'confirmed' parameter is unexplained, the prerequisite sibling is only implied, and non-idempotency error cases (e.g., invalid/expired confirmation) are not mentioned.

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%, so the description must compensate. It explains idempotencyKey semantics thoroughly (first-key binding, retry with same key) and touches confirmationId ('retry with the same confirmationId'), but the required 'confirmed' boolean is never addressed beyond the vague implication of 'explicit user approval'. One parameter is richly covered, one partially, one not at all.

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 the hosted Stripe payment link') and scopes it with the precondition 'use the prepared confirmation', which distinguishes this step from checkout_prepare_payment. An agent can tell it is the final materialization step rather than the preparation 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?

Clearly says when to call it ('After explicit user approval', with 'the prepared confirmation') and gives retry conditions ('retry with the same confirmationId and exact same key; do not switch keys'). It implies the prerequisite sibling but never explicitly names checkout_prepare_payment or states when not to use it.

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