{
    "action": "tool_call",
    "reasoning": "The question asks about natural segmentation/grouping of records. The overview confirms ae and adsl are semantically related (subjects and their adverse events) but technically disconnected. I need to understand what columns exist on each table to identify natural grouping dimensions. The card says column ownership is not listed and I should call inspect_columns before referencing columns. I'll start with adsl since it's the dimension/subject table and likely contains the primary segmentation variables (demographics, treatment arms, etc.).",
    "tool": "inspect_columns",
    "args": {
        "table": "adsl"
    }
}