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

Annotations already declare destructive and open-world behavior; the description adds genuine value beyond them by disclosing the returned URL/reference, that approval happens on an external page, that zero-amount carts complete immediately, and that an unchanged cart returns the same payment link (idempotency). It stops short of explaining what state is affected on the cart or store once checkout starts.

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, front-loaded sentences with no wasted words: purpose and payment types first, then return value, then edge cases. Every sentence carries useful information.

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 an output schema present, the description doesn't need to explain return values but still usefully summarizes them. It covers the external approval flow, zero-amount edge case, and idempotency; the main gap is the absence of guidance on post-checkout verification via checkout_verify.

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 coverage is 100%, and both parameters (storeId, paymentType) are already documented in the schema. The description reinforces the paymentType restriction ('Dintero or DinteroVipps') but adds nothing beyond the schema, so the baseline of 3 applies.

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 ('Start checkout') and confines the supported payment types to Dintero or DinteroVipps. It does not name the checkout_verify sibling, but the flow it describes (guest approves on Dintero's page) makes the initiate step distinguishable from verification.

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 implies this is the payment-initiation step but never says when to prefer it over alternatives or what to do after (e.g., call checkout_verify to poll status). There are no explicit when-not-to-use conditions or prerequisites such as cart being non-empty at the start.

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