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

# cart_add

> Add one item to an open cart.

One call per item. Restaurant dishes with required choices (size, sides) need the buyer's picks.

| | |
| - | - |
| 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
Adds one shop offer to an open cart. One cart holds one shop; restricted categories and quantities above available stock are refused. Restaurant items with required options need modifiers, and the error lists the available choices. Nothing is reserved or charged.
```

## Parameters

| Name | Type | Required | Description |
| - | - | - | - |
| `cart_id` | `uuid` | Yes | The cart. |
| `product_id` | `uuid` | Yes | The offer, from a search result. |
| `qty` | `integer` | No | How many, 1 to 99. Left out: 1. |
| `weight_lb` | `number` | No | For items sold by weight (`sold_by: weight` in search results): how many pounds, in 0.25 lb steps. Left out: ask by count with `qty`. |
| `modifiers` | `object[]` | No | Menu options for restaurant items, listed under `modifier_groups` in search results. One entry per group: `group_id` and the `option_ids` the buyer picked. Every required group needs an answer. |
| `note` | `string` | No | Restaurant items only: the buyer's short note for this item, such as "No onions". At most 140 characters. |
| `substitution_policy` | `string` | No | `never_substitute`, `ask_first` or `auto_similar`. |

## Notes

- A required option group left out comes back as `MISSING_FIELD` on `modifiers`, with the groups and their choices. Ask the buyer; never send the example call as it is.
- Adding an item clears any approval the cart already had.