{
    "action": "tool_call",
    "reasoning": "I will query the analytics.column_overview table to get the list of columns, their physical data types, and their semantic roles (meanings) for the main table in the dataset, raw.cleandata.",
    "tool": "query_sql",
    "args": {
        "purpose": "Get columns, types, and meanings for raw.cleandata",
        "source": "raw",
        "sql": "SELECT column_name, phys_type, semantic_role FROM analytics.column_overview WHERE table_name = 'raw.cleandata'"
    }
}