replace full {}

https://www.googleapis.com/youtube/v3/videos?key={API_KEY}fields=items(snippet(title,description,tags))&part=snippet&id={VIDEO_ID}

{
 "items": [
  {
   "snippet": {
    "title": "Testvideo",
    "description": "blablabla",
    "tags": [
     "Lunetikk",
     "Xbox One X",
     "DPS Lunetikk"
    ]
   }
  }
 ]
}