diff --git a/libs/core/tests/unit_tests/test_tools.py b/libs/core/tests/unit_tests/test_tools.py
index c104b9964ed..65effa69e03 100644
--- a/libs/core/tests/unit_tests/test_tools.py
+++ b/libs/core/tests/unit_tests/test_tools.py
@@ -2355,7 +2355,7 @@ def test_tool_injected_tool_call_id_override_llm_generated() -> None:
     @tool
     def foo(x: int, tool_call_id: Annotated[str, InjectedToolCallId]) -> ToolMessage:
         """Foo."""
-        return ToolMessage(x, tool_call_id=tool_call_id)  # type: ignore[arg-type]
+        return ToolMessage(str(x), tool_call_id=tool_call_id)
 
     # Test that when LLM generates the tool_call_id, it gets overridden
     result = foo.invoke(
@@ -2368,14 +2368,14 @@ def test_tool_injected_tool_call_id_override_llm_generated() -> None:
     )
 
     # The tool should receive the real tool call ID, not the LLM-generated one
-    assert result == ToolMessage(0, tool_call_id="real_tool_call_id")  # type: ignore[arg-type]
+    assert result == ToolMessage("0", tool_call_id="real_tool_call_id")
 
 
 def test_tool_uninjected_tool_call_id() -> None:
     @tool
     def foo(x: int, tool_call_id: str) -> ToolMessage:
         """Foo."""
-        return ToolMessage(x, tool_call_id=tool_call_id)  # type: ignore[call-overload]
+        return ToolMessage(str(x), tool_call_id=tool_call_id)
 
     with pytest.raises(ValueError, match="1 validation error for foo"):
         foo.invoke({"type": "tool_call", "args": {"x": 0}, "name": "foo", "id": "bar"})