{
    "action": "tool_call",
    "reasoning": "I will query the column overview to get a complete list of columns, their data types, and their semantic roles to explain what each one means.",
    "tool": "query_sql",
    "args": {
        "purpose": "Get all columns, data types, and semantic roles",
        "source": "raw",
        "sql": "SELECT column_name, phys_type, semantic_role FROM analytics.column_overview WHERE table_name = 'ai_supercomputers' ORDER BY column_name"
    }
}