add_item_to_cart

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

No annotations are provided, so the description carries the behavioral transparency burden. It discloses the mutation semantics ('adds or updates'), the authentication requirement, and the return value ('updated cart totals and summary'). It does not discuss failure behavior or explicitly state that the quantity replaces rather than increments an existing item, but the essential side effects are covered.

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 description is front-loaded with the main verb and resource, and each sentence adds a distinct piece of information: action, parameters, tracking, return value, and auth requirement. It is slightly verbose and could be tightened, but it is not redundant.

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?

The description covers the action, auth requirement, and return information, which is important given no output schema. However, it does not address the sibling `add_item_to_cart_by_ean`, error/unauthenticated behavior, or clarify whether `counter` sets or increments quantity, leaving some ambiguity for a mutation 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 description coverage is 100%, so the schema already documents each parameter. The description adds grouping and context, such as 'basket service (store/drive)', 'sub-basket type (e.g. drive click-and-collect)', and 'tracking context', but it does not significantly expand beyond the schema definitions.

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 opening sentence names a specific action ('Adds or updates') and resource ('product item in the authenticated user's cart on Carrefour France'), and the description adds EAN, quantity, basket service, and sub-basket type. However, it does not distinguish this tool from the sibling `add_item_to_cart_by_ean`, so it stops short of full sibling differentiation.

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 provides clear usage context: this is for adding or updating cart items under an authenticated Carrefour session, with optional tracking context. It does not provide explicit when-not-to-use guidance or name an alternative such as `add_item_to_cart_by_ean`, so it earns 4 rather than 5.

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