create_cart

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

With no annotations, the description carries the full burden and does so: it discloses that nothing is purchased without a passkey approval, that approval happens out-of-band via a link/QR in the result, and that the response ends with what the gateway sent to Intent Cloud and what it blocked. These are exactly the behavioral facts an agent cannot get from structured fields.

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-loads the action and its input source, then layers the non-purchase guarantee, the conditional quantity rule, the delivery constraint, and the return content. Every sentence adds a distinct fact with no padding.

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?

Despite no output schema, the description summarizes what the result contains (approval link/QR plus the gateway payload and blocked items), and covers prerequisites, locality limits, and the fact that approval is a separate human step. Nothing an agent needs to invoke this safely is missing.

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%, so the baseline is 3, but the description adds real semantic guidance beyond the schema: quantity should only be passed when the user explicitly asked for it, and offer_handle must come from find_offers. This is useful conditional nuance the pattern/range constraints don't convey.

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 ('Prepare a cart') and ties the input directly to its sibling by requiring the offer_handle from find_offers. It also immediately disambiguates from purchasing, so an agent can tell this apart from any buy/checkout tool without opening the schema.

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?

Gives clear conditions: use the offer_handle returned by find_offers, pass quantity only if the user asked, and US delivery only. It does not explicitly name get_approval_status as the follow-up tool, leaving the post-creation workflow to be inferred from the mention of an approval link/QR.

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