Please review proper request headers here.  
Parameters
Only return tags for this merchant
 
Response
Array of attribute tags. Currently, only string tags are supported.
 
curl https://api.thanxsandbox.com/tags \
  -X PUT \
  -H "Content-Type: application/json"  \
  -H "Accept-Version: v4.0" \
  -H "Accept: application/json" \
  -H "Authorization: Bearer ${token}" \
  -H "X-ClientId: ${client_id}" 
  -d '{
    "tag": {
      "key": "allergens",
      "merchant_id": "weroifs",
      "values": [
        "gluten",
        "soy",
        "dairy",
        "honey"
      ]
    }
  }'
 
{
  "tag": {
    "id": "werwerr",
    "user_id": "werofsdf",
    "merchant_id": "weroif",
    "key": "allergens",
    "values": ["gluten", "soy", "dairy", "honey"]
  }
}