diff --git a/src/nr_openai_observability/langchain_callback.py b/src/nr_openai_observability/langchain_callback.py
index f6bdaa4..0e284ef 100644
--- a/src/nr_openai_observability/langchain_callback.py
+++ b/src/nr_openai_observability/langchain_callback.py
@@ -139,7 +139,7 @@ def on_chain_error(
         self, error: Union[Exception, KeyboardInterrupt], **kwargs: Any
     ) -> Any:
         """Run when chain errors."""
-        tags = {error: str(error)}
+        tags = {"error": str(error)}
         span = self.spans_stack.pop()
         assert span["attributes"]["name"] == "LlmChain"
         self.finish_and_record_span(span, tags)
@@ -173,9 +173,7 @@ def on_tool_error(
         self, error: Union[Exception, KeyboardInterrupt], **kwargs: Any
     ) -> Any:
         """Run when tool errors."""
-        tags = {
-            "error": error,
-        }
+        tags = {"error": str(error)}
         span = self.spans_stack.pop()
         assert span["attributes"]["name"] == "LlmTool"
         tool_name = kwargs.get("name")