From 15f0ac750610aefdc06daba87d9881a9f6a17071 Mon Sep 17 00:00:00 2001
From: David Padbury <padbury@amazon.com>
Date: Thu, 11 Dec 2025 17:40:19 -0600
Subject: [PATCH 1/2] fix: close mcp client event loop

---
 src/strands/tools/mcp/mcp_client.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/strands/tools/mcp/mcp_client.py b/src/strands/tools/mcp/mcp_client.py
index bb5dca19c..7aa57a39f 100644
--- a/src/strands/tools/mcp/mcp_client.py
+++ b/src/strands/tools/mcp/mcp_client.py
@@ -330,6 +330,9 @@ async def _set_close_event() -> None:
             self._log_debug_with_thread("waiting for background thread to join")
             self._background_thread.join()
 
+            if self._background_thread_event_loop is not None:
+                self._background_thread_event_loop.close()
+
         self._log_debug_with_thread("background thread is closed, MCPClient context exited")
 
         # Reset fields to allow instance reuse

From 169b62476b08582e672a2be7671ba71fe597f677 Mon Sep 17 00:00:00 2001
From: Dean Schmigelski <dbschmigelski+github@gmail.com>
Date: Fri, 12 Dec 2025 10:21:06 -0500
Subject: [PATCH 2/2] feat: close event loop regardless of if thread exists

---
 src/strands/tools/mcp/mcp_client.py        |  4 ++--
 tests/strands/tools/mcp/test_mcp_client.py | 27 ++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/strands/tools/mcp/mcp_client.py b/src/strands/tools/mcp/mcp_client.py
index 7aa57a39f..7a26cdd6b 100644
--- a/src/strands/tools/mcp/mcp_client.py
+++ b/src/strands/tools/mcp/mcp_client.py
@@ -330,8 +330,8 @@ async def _set_close_event() -> None:
             self._log_debug_with_thread("waiting for background thread to join")
             self._background_thread.join()
 
-            if self._background_thread_event_loop is not None:
-                self._background_thread_event_loop.close()
+        if self._background_thread_event_loop is not None:
+            self._background_thread_event_loop.close()
 
         self._log_debug_with_thread("background thread is closed, MCPClient context exited")
 
diff --git a/tests/strands/tools/mcp/test_mcp_client.py b/tests/strands/tools/mcp/test_mcp_client.py
index ec77b48a2..e72aebd92 100644
--- a/tests/strands/tools/mcp/test_mcp_client.py
+++ b/tests/strands/tools/mcp/test_mcp_client.py
@@ -524,6 +524,33 @@ def test_stop_with_background_thread_but_no_event_loop():
     assert client._background_thread is None
 
 
+def test_stop_closes_event_loop():
+    """Test that stop() properly closes the event loop when it exists."""
+    client = MCPClient(MagicMock())
+
+    # Mock a background thread with event loop
+    mock_thread = MagicMock()
+    mock_thread.join = MagicMock()
+    mock_event_loop = MagicMock()
+    mock_event_loop.close = MagicMock()
+    
+    client._background_thread = mock_thread
+    client._background_thread_event_loop = mock_event_loop
+
+    # Should close the event loop and join the thread
+    client.stop(None, None, None)
+
+    # Verify thread was joined
+    mock_thread.join.assert_called_once()
+    
+    # Verify event loop was closed
+    mock_event_loop.close.assert_called_once()
+
+    # Verify cleanup occurred
+    assert client._background_thread is None
+    assert client._background_thread_event_loop is None
+
+
 def test_mcp_client_state_reset_after_timeout():
     """Test that all client state is properly reset after timeout."""