curl --request GET \
  --url https://api.ask.surf/gateway/v1/onchain/schema

{
  "data": [
    {
      "columns": [
        {
          "name": "<string>",
          "type": "<string>",
          "comment": "<string>"
        }
      ],
      "database": "<string>",
      "table": "<string>"
    }
  ],
  "meta": {
    "cached": true,
    "credits_used": 123,
    "limit": 123,
    "offset": 123,
    "total": 123
  },
  "$schema": "<string>"
}