diff --git a/agentops/instrumentation/providers/openai/attributes/response.py b/agentops/instrumentation/providers/openai/attributes/response.py
index 9cf8f4b80..0b07dad83 100644
--- a/agentops/instrumentation/providers/openai/attributes/response.py
+++ b/agentops/instrumentation/providers/openai/attributes/response.py
@@ -462,9 +462,9 @@ def get_response_output_message_attributes(index: int, message: "ResponseOutputM
     attributes = _extract_attributes_from_mapping_with_index(message, RESPONSE_OUTPUT_MESSAGE_ATTRIBUTES, index)
 
     if message.content:
-        for i, content in enumerate(message.content):
+        for content in message.content:
             if isinstance(content, ResponseOutputText):
-                attributes.update(get_response_output_text_attributes(content, i))
+                attributes.update(get_response_output_text_attributes(content, index))
 
             else:
                 logger.debug(
diff --git a/tests/unit/instrumentation/openai_core/test_response_attributes.py b/tests/unit/instrumentation/openai_core/test_response_attributes.py
index 24809423f..250138683 100644
--- a/tests/unit/instrumentation/openai_core/test_response_attributes.py
+++ b/tests/unit/instrumentation/openai_core/test_response_attributes.py
@@ -10,6 +10,8 @@
 import os
 from unittest.mock import MagicMock, patch
 
+from openai.types.responses import ResponseOutputMessage, ResponseOutputText, ResponseReasoningItem
+
 from agentops.instrumentation.providers.openai.attributes.response import (
     get_response_kwarg_attributes,
     get_response_response_attributes,
@@ -400,6 +402,35 @@ def test_get_response_output_message_attributes(self):
             # Verify basic expected attributes
             assert isinstance(result, dict)
 
+    def test_response_message_content_uses_parent_output_index(self):
+        """Message text must share the parent output item's completion index."""
+        reasoning = ResponseReasoningItem(
+            id="reasoning_1",
+            summary=[],
+            type="reasoning",
+            status="completed",
+        )
+        message = ResponseOutputMessage(
+            id="msg_1",
+            content=[
+                ResponseOutputText(
+                    annotations=[],
+                    text="answer",
+                    type="output_text",
+                )
+            ],
+            role="assistant",
+            status="completed",
+            type="message",
+        )
+
+        attributes = get_response_output_attributes([reasoning, message])
+
+        assert attributes[MessageAttributes.COMPLETION_ID.format(i=0)] == "reasoning_1"
+        assert MessageAttributes.COMPLETION_CONTENT.format(i=0) not in attributes
+        assert attributes[MessageAttributes.COMPLETION_ID.format(i=1)] == "msg_1"
+        assert attributes[MessageAttributes.COMPLETION_CONTENT.format(i=1)] == "answer"
+
     def test_get_response_output_text_attributes(self):
         """Test extraction of attributes from output text"""
         # Create a mock text content