diff --git a/mcp_clickhouse/mcp_server.py b/mcp_clickhouse/mcp_server.py
index 244a6cd..c2a0fdf 100644
--- a/mcp_clickhouse/mcp_server.py
+++ b/mcp_clickhouse/mcp_server.py
@@ -137,15 +137,8 @@ def execute_query(query: str):
     try:
         read_only = get_readonly_setting(client)
         res = client.query(query, settings={"readonly": read_only})
-        column_names = res.column_names
-        rows = []
-        for row in res.result_rows:
-            row_dict = {}
-            for i, col_name in enumerate(column_names):
-                row_dict[col_name] = row[i]
-            rows.append(row_dict)
-        logger.info(f"Query returned {len(rows)} rows")
-        return rows
+        logger.info(f"Query returned {len(res.result_rows)} rows")
+        return {"columns": res.column_names, "rows": res.result_rows}
     except Exception as err:
         logger.error(f"Error executing query: {err}")
         # Return a structured dictionary rather than a string to ensure proper serialization
diff --git a/tests/test_tool.py b/tests/test_tool.py
index e931c3f..94899ea 100644
--- a/tests/test_tool.py
+++ b/tests/test_tool.py
@@ -62,10 +62,10 @@ def test_run_select_query_success(self):
         """Test running a SELECT query successfully."""
         query = f"SELECT * FROM {self.test_db}.{self.test_table}"
         result = run_select_query(query)
-        self.assertIsInstance(result, list)
+        self.assertIsInstance(result, dict)
         self.assertEqual(len(result), 2)
-        self.assertEqual(result[0]["id"], 1)
-        self.assertEqual(result[0]["name"], "Alice")
+        self.assertEqual(result["rows"][0][0], 1)
+        self.assertEqual(result["rows"][0][1], "Alice")
 
     def test_run_select_query_failure(self):
         """Test running a SELECT query with an error."""