update_quantity

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

No annotations are provided, so the description carries the burden. It discloses the key constraint that the product must already be in the cart, which is a behavioral trait. However, it does not mention that setting quantity to 0 removes the item (though the schema does), nor does it describe error behavior for a missing product ID. This is a clear gap.

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 a single, concise sentence in French. It front-loads the action and avoids unnecessary wording, making it easy to scan and understand.

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 only 2 parameters, both fully described in the schema, and no output schema, the description provides the essential purpose and a key constraint. It is adequate for an agent to invoke the tool correctly, though it could mention return values or failure modes. For a simple cart operation, a 4 is justified.

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?

The input schema provides descriptions for both required parameters (quantity and product_id) with 100% coverage. The description adds no extra parameter information beyond the schema, so the baseline score of 3 is appropriate.

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 clearly states the action ('Modifie' = modifies) and the resource ('la quantité d'un produit déjà présent dans le panier' = the quantity of a product already in the cart). It explicitly distinguishes this tool from siblings like add_to_cart and remove_from_cart by noting the product must already be in the cart.

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 implies the tool is for updating an existing cart item's quantity, which gives clear usage context relative to add/remove siblings. However, it does not explicitly name alternative tools or state when not to use it, so it stops short of full guidance.

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