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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds behavior annotations do not: payment method availability differs between a confirmed email (path A, bank transfer included) and pre-confirmation (path B, card/iDEAL/Bancontact, pay first), and the order is locked while a payment is open. Auth via Authorization: Bearer mo1_… or the ref argument is also disclosed.

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?

The content is dense but the opening sentence is a long list that trails off into 'and next', which reads as broken or truncated and forces the agent to infer the verb. Later sentences are well-formed and the payment-lock warning is front-loaded appropriately, but the lead sentence should have started with what the tool does.

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?

There is no output schema, so the field enumeration (lines, totals, addresses, shipping, payment methods) does real work in telling the agent what comes back. Authentication and the reference source are both covered. Error or empty-checkout behavior is not described, which is a minor gap for a read-only tool.

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 the single ref parameter is already documented as the start_order reference for clients that cannot send the header. The description reinforces this by naming the Bearer mo1_… header as the primary mechanism and ref as the fallback, clarifying precedence rather than duplicating it.

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 enumerates exactly what the call returns (lines, totals in storefront currency, address snapshot, shipping methods with prices, allowed payment methods), so an agent knows this is a read of the order's checkout state. It also names check_payment, cancel_payment and start_order, which separates it from those siblings. It never states the retrieving verb explicitly, relying on the tool name to carry that.

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 real routing context: while a payment is open the order is not editable and the agent should look at check_payment or cancel_payment instead. It also says the order reference comes from start_order. What is missing is a direct statement of when view_checkout itself is the right call versus set_checkout or place_order.

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