{
  "name": "sockets.users.count",
  "description": "Counts connected socket users, optionally filtered by username",
  "signature": {
    "children": {
      "filter": {
        "type": "string",
        "kind": "username",
        "description": "Username filter",
        "required": false,
        "mode": "ValueOrExpression",
        "cardinality": "ZeroOrOne",
        "role": "Option",
        "projection": "Value"
      }
    },
    "output": {
      "mode": "Value",
      "kind": "integer,number",
      "description": "Resolves to the number of connected socket users matching the optional filter"
    }
  }
}