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

Goes well beyond the annotations (which only say it is a non-idempotent, non-destructive, open-world write) by disclosing the side effect of one confirmation email to the shopper and the requirement to ask them first. It also explains the lifetime and scoping of the returned reference: endpoint-specific, expiring 30 days after last use, or 7 days while unconfirmed.

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?

Front-loaded with the action, then credentials, then the returned reference and its lifetime — a logical order with no filler sentences. It is dense, with long parenthetical clauses, but every clause carries operational meaning.

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 carries the return contract (order reference mo1_…), how to present it on later calls, and its expiration semantics. For a two-parameter entry-point tool, an agent has everything needed to invoke it and reuse its result.

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 already 100%, so the baseline is 3; the description earns above that by explaining the consequence of each choice — the email path triggers a confirmation email to the shopper, while the key is an alternative they created on their account. It does not add format or validation detail for either value.

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?

"Start an order for the shopper on this storefront" names a specific verb and resource, and the credential/return-value details make the entry-point nature unambiguous. It stops short of naming the sibling it differs from (place_order, set_checkout), so an agent must infer that this opens rather than completes a checkout.

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 rather than stated: the caller learns it needs an email or connection key and that consent should be obtained first, which is useful prerequisite guidance. However, there is no explicit when-to-use versus place_order, view_checkout, or order_history, and no statement that this must precede those calls.

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