APi query can not work for uid

[root@dx-app ~]# curl -sS -H "Authorization: Bearer $KEY" localhost:3000/api/search?query=aa | jq
[
  {
    "id": 25,
    "uid": "SsymwCTik",
    "title": "aa",
    "uri": "db/aa",
    "url": "/dashboards/f/SsymwCTik/aa",
    "type": "dash-folder",
    "tags": [],
    "isStarred": false
  }
]
[root@dx-app ~]# curl -sS -H "Authorization: Bearer $KEY" localhost:3000/api/search?query=Ss | jq
[]

As above, seems query API can not work for uid, is it a design?

Is there a good way to query by uid?

Also, it could be better if show which area can query in docs.