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

Annotations already declare non-readonly, non-idempotent, non-destructive, open-world. The description adds genuinely new behavior: the cart is empty at creation, no login is required, and the guest_token is private and must be retained for later cart/checkout calls. That is useful workflow context beyond the structured hints.

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?

Four short sentences, front-loaded with the action and scope, followed by the retention/usage instructions. No filler and nothing redundant with the annotations.

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 carries the burden of describing what comes back and does so (cart_id, version, guest_token). Combined with annotations covering the safety profile and a fully documented single parameter, an agent has everything needed to call it and use the 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 100%, so baseline is 3, but the description adds downstream meaning for guest_token (retain it and pass it on later shopping calls) rather than just restating the type. The only weakness is that it frames guest_token primarily as something to 'save' from the response, which slightly blurs its role as an optional input.

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 ('Create an empty persistent cart') plus the key scope qualifier 'without account login', which separates it from create_checkout and get_cart. It does not name a sibling explicitly, so an agent must infer the boundary from the guest-vs-account distinction.

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 operational context: create first, then pass guest_token on subsequent shopping calls, with account authentication optional. It does not explicitly say when to prefer create_cart over create_checkout, but the guest/no-login framing makes the choice reasonably evident.

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