add_item_to_cart_by_ean

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

No annotations are provided, so the description must carry the behavioral disclosure burden. It states that it adds a product and returns updated cart totals and summary, but it does not disclose side effects like overwriting existing cart state, failure behavior, or whether an invalid EAN could partially modify a cart.

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 two sentences, front-loaded with the primary action, and economical. Every phrase adds value: the EAN method, the required service IDs, the tracking context, the return value, and the authentication note.

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?

Given the moderate complexity of the tool, the description covers the main purpose, parameters, return value, and authentication prerequisite. It could be more complete by mentioning what happens if the EAN is invalid or session expired, but the provided information is sufficient for a competent selection decision.

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 each parameter has a clear description. The tool description adds the real-world meaning of basketServiceId and subBasketType with an example ('drive_clcv' for drive click-and-collect), and the tracking context for pageType/pageId, which complements the schema.

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 uses a specific verb ('Adds') and clearly states the resource (authenticated user's cart on Carrefour France), the key identifier (EAN), and required context (basket service ID, sub-basket type). It distinguishes itself from the sibling `add_item_to_cart` by specifying the EAN-based method and the Carrefour France scope.

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?

The description clarifies that it requires an authenticated Carrefour session, which helps the agent know when this tool is applicable vs. needing `carrefour_refresh_session` or `carrefour_browser_login`. It does not explicitly name sibling alternatives, but the EAN-specific phrasing and authenticated-session requirement provide useful context.

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