{
    "action": "tool_call",
    "reasoning": "The question asks about natural segmentation/grouping opportunities. The overview shows beer_ratings dominates (85% of rows), but I need to understand what dimensions exist for grouping. The card shows temporal axes across multiple tables and spatial axes. Let me start by examining the largest table (beer_ratings) to see what categorical/grouping columns it contains, then look at the reference tables (beers, users, brewers) that would provide natural segments.",
    "tool": "inspect_columns",
    "args": {
        "table": "beer_ratings"
    }
}