To update a deal, following permissions are required.

Deal permission: the user should have a permission to manage deals.
Pipeline-specific permission: the user should have a permission to manage the pipeline the updating deal belongs to.
Deal reassign permission: if assigning the deal to another user, this permission is required.

By default, the deal stage is also returned in the response. If deal.contact was provided in the request, the primary contact is also returned in the response.

📘
Deal Status ID's
0 = Open
1 = Won
2 = Lost

{
  "deal": {
    "contact": "51",
    "account": "45",
    "description": "This deal is an important deal",
    "currency": "usd",
    "group": "1",
    "owner": "1",
    "percent": null,
    "stage": "1",
    "status": 0,
    "title": "AC Deal",
    "value": 45600,
    "fields": [
      {
        "customFieldId": 1,
        "fieldValue": "First field value"
      },
      {
        "customFieldId": 2,
        "fieldValue": "2008-01-20"
      },
      {
        "customFieldId": 3,
        "fieldValue": 8800,
        "fieldCurrency": "USD"
      }
    ]
  }
}