diff --git a/litellm/llms/prompt_templates/factory.py b/litellm/llms/prompt_templates/factory.py
index bbf87ca49f7..6658671f8e6 100644
--- a/litellm/llms/prompt_templates/factory.py
+++ b/litellm/llms/prompt_templates/factory.py
@@ -698,8 +698,10 @@ def anthropic_messages_pt_xml(messages: list):
             if messages[msg_i].get(
                 "tool_calls", []
             ):  # support assistant tool invoke convertion
-                assistant_text += convert_to_anthropic_tool_invoke(  # type: ignore
-                    messages[msg_i]["tool_calls"]
+                assistant_content.extend(
+                    convert_to_anthropic_tool_invoke(  # type: ignore
+                        messages[msg_i]["tool_calls"]
+                    )
                 )
 
             assistant_content.append({"type": "text", "text": assistant_text})