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

Annotations declare non-read-only, non-destructive, closed-world, but the description adds genuinely new behavior: the intent is short-lived and signed, and no account is created until the user completes the first-party page. That clarifies side effects and the handoff, which the annotations alone do not convey. It doesn't state token TTL or what happens on expiry.

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 tightly written sentences: the action and return value are front-loaded, followed by the handoff context. Nothing is redundant.

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?

The flow context is well explained and no output schema exists so return values are covered by the URL mention. However, with a nested domainIntent object and zero parameter documentation, an agent lacks enough to build correct arguments beyond guessing from names.

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% and four parameters (productRef, billingCycle, domainIntent with mode/domain, promotionCode) are documented only by their types and patterns. The description mentions 'product-selection' vaguely but never explains what productRef accepts, what domainIntent modes mean, or how promotionCode is applied, so it fails to compensate for the coverage gap.

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?

Specific verb+resource: creates a short-lived signed product-selection intent and returns a continuation URL. It conveys the tool's role as the entry point to checkout, though it never names the siblings it differs from (quote_public_product, recommend_product).

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?

Usage is implied by 'signup/checkout' and the note that account creation and payment happen on the continuation page, which signals this is a pre-checkout step. There is no explicit when-not or routing to quote/recommend siblings, so the agent must infer that this is the terminal 'start purchase' action rather than a pricing call.

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