curl --request GET \
  --url https://api.box.com/2.0/metadata_taxonomies/{namespace} \
  --header 'Authorization: Bearer <token>'

{
  "limit": 1000,
  "next_marker": "JV9IRGZmieiBasejOG9yDCRNgd2ymoZIbjsxbJMjIs3kioVii",
  "prev_marker": "JV9IRGZmieiBasejOG9yDCRNgd2ymoZIbjsxbJMjIs3kioVih",
  "entries": [
    {
      "id": "822227e0-47a5-921b-88a8-494760b2e6d2",
      "displayName": "Geography",
      "namespace": "enterprise_123456",
      "key": "geography",
      "levels": [
        {
          "displayName": "Continent",
          "description": "Continent",
          "level": 1
        }
      ]
    }
  ]
}