diff --git a/ctapipe/core/tool.py b/ctapipe/core/tool.py
index 5d28c1585a3..9a83d76a5dc 100644
--- a/ctapipe/core/tool.py
+++ b/ctapipe/core/tool.py
@@ -419,7 +419,9 @@ def run(self, argv=None, raises=False):
 
                 # check for any traitlets warnings using our custom handler
                 if len(self.trait_warning_handler.errors) > 0:
-                    raise ToolConfigurationError("Found config errors")
+                    raise ToolConfigurationError(
+                        f"Found config errors: {self.trait_warning_handler.errors}"
+                    )
 
                 # remove handler to not impact performance with regex matching
                 self.log.removeHandler(self.trait_warning_handler)