Avoid leaking output validation errors

lib/crewai/src/crewai/tools/structured_tool.py

@@ -74,7 +74,8 @@ def _format_tool_output_for_agent(tool: Any, raw_result: Any) -> str:
             (
                 f"Failed to validate or serialize output from tool "
                 f"'{getattr(tool, 'name', '<unknown>')}' using output_schema "
-                f"'{output_schema.__name__}': {exc}. Falling back to str(raw_result)."
+                f"'{output_schema.__name__}': {exc.__class__.__name__}. "
+                "Falling back to str(raw_result)."
             ),
             RuntimeWarning,
             stacklevel=2,

lib/crewai/tests/tools/test_structured_tool.py

@@ -188,11 +188,16 @@ def test_invalid_typed_output_warns_and_uses_string_agent_text():
     )
     raw_result = tool.invoke({"value": "crew"})
 
-    with pytest.warns(RuntimeWarning, match="Failed to validate or serialize"):
+    with pytest.warns(
+        RuntimeWarning, match="Failed to validate or serialize"
+    ) as warnings:
         agent_text = tool.format_output_for_agent(raw_result)
 
     assert raw_result == {"value": "crew", "count": "wrong"}
     assert agent_text == str(raw_result)
+    warning_message = str(warnings[0].message)
+    assert "ValidationError" in warning_message
+    assert "wrong" not in warning_message
 
 
 def test_validate_function_signature(basic_function, schema_class):