diff --git a/tools/browser_tool.py b/tools/browser_tool.py
index 351ba1dc20..d64893d988 100644
--- a/tools/browser_tool.py
+++ b/tools/browser_tool.py
@@ -3392,6 +3392,8 @@ def _pid_exists(pid: int) -> bool:
             return psutil.pid_exists(pid)
         except Exception:
             return False
+    # windows-footgun: ok — psutil.pid_exists above handles Windows; this
+    # os.kill(pid, 0) probe only runs when psutil is unavailable.
     try:
         os.kill(pid, 0)
     except ProcessLookupError: