> Documentation index: https://www.xekta.com/llms.txt

# cart_set_quantity

> Lower the quantity of a cart line or remove it.

Use `qty: 0` to remove a line.

| | |
| - | - |
| Type | Write: changes a cart or an order |
| Needs a cart the buyer approved | No |
| Moves money | No |

**Tool description (what the assistant sees)**

```text
Lowers the quantity of one cart line or removes it (qty 0). For items sold by weight, weight_lb (or qty) sets the amount up or down, replacing the earlier amount. When the same item appears on several lines with different options, line_id selects one. Any change clears the buyer's approval of the cart. Nothing is reserved or charged.
```

## Parameters

| Name | Type | Required | Description |
| - | - | - | - |
| `cart_id` | `uuid` | Yes | The cart. |
| `product_id` | `uuid` | Yes | The item to change. |
| `qty` | `integer` | No | The new quantity, 0 to 99. 0 removes the line. |
| `weight_lb` | `number` | No | For items sold by weight: the new amount in pounds, in 0.25 lb steps. It replaces the earlier amount. |
| `line_id` | `uuid` | No | Which line to change when the cart has more than one line of this product, for example two burgers with different options. |