diff --git a/tools/delegate_tool.py b/tools/delegate_tool.py
index 67963b2cecc..50f58c1a0d2 100644
--- a/tools/delegate_tool.py
+++ b/tools/delegate_tool.py
@@ -2094,8 +2094,11 @@ def _run_single_child(
                     _err = (
                         f"Subagent timed out after {child_timeout}s with "
                         f"{child_api_calls} API call(s) completed — likely "
-                        f"stuck on a slow API call or unresponsive network request."
+                        f"stuck on a slow API call, tool call, or unresponsive "
+                        f"network request."
                     )
+                    if diagnostic_path:
+                        _err += f" Diagnostic: {diagnostic_path}"
             else:
                 _err = str(_timeout_exc)
 
@@ -2107,6 +2110,13 @@ def _run_single_child(
                 "exit_reason": "timeout" if is_timeout else "error",
                 "api_calls": child_api_calls,
                 "duration_seconds": duration,
+                "timeout_seconds": child_timeout if is_timeout else None,
+                "timed_out_after_seconds": duration if is_timeout else None,
+                "timeout_phase": (
+                    "before_first_llm_call" if is_timeout and child_api_calls == 0
+                    else "after_llm_calls" if is_timeout
+                    else None
+                ),
                 "_child_role": getattr(child, "_delegate_role", None),
                 "diagnostic_path": diagnostic_path,
             }