From acbb0874ea31b01e00c74f8d83791d73e65c1c0f Mon Sep 17 00:00:00 2001
From: Erick Friis <erick@langchain.dev>
Date: Thu, 19 Dec 2024 13:09:17 -0500
Subject: [PATCH] x

---
 libs/core/tests/unit_tests/test_tools.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/libs/core/tests/unit_tests/test_tools.py b/libs/core/tests/unit_tests/test_tools.py
index b331abea7da7a..d60defceadcdd 100644
--- a/libs/core/tests/unit_tests/test_tools.py
+++ b/libs/core/tests/unit_tests/test_tools.py
@@ -2255,3 +2255,20 @@ def foo(x: int) -> Bar:
     assert foo.invoke(
         {"type": "tool_call", "args": {"x": 0}, "name": "foo", "id": "bar"}
     ) == Bar(x=0)
+
+
+def test_tool_mutate_input() -> None:
+    class MyTool(BaseTool):
+        name: str = "MyTool"
+        description: str = "a tool"
+
+        def _run(
+            self,
+            x: str,
+            run_manager: Optional[CallbackManagerForToolRun] = None,
+        ) -> str:
+            return "hi"
+
+    my_input = {"x": "hi"}
+    MyTool().invoke(my_input)
+    assert my_input == {"x": "hi"}