diff --git a/chatkit/agents.py b/chatkit/agents.py
index 37668e7..4d307d7 100644
--- a/chatkit/agents.py
+++ b/chatkit/agents.py
@@ -7,7 +7,6 @@
     Annotated,
     Any,
     AsyncGenerator,
-    Awaitable,
     Generic,
     Sequence,
     TypeVar,
@@ -634,9 +633,9 @@ class ThreadItemConverter:
     Other item types are converted automatically.
     """
 
-    def attachment_to_message_content(
+    async def attachment_to_message_content(
         self, attachment: Attachment
-    ) -> Awaitable[ResponseInputContentParam]:
+    ) -> ResponseInputContentParam:
         """
         Convert an attachment in a user message into a message content part to send to the model.
         Required when attachments are enabled.
@@ -645,7 +644,7 @@ def attachment_to_message_content(
             "An Attachment was included in a UserMessageItem but Converter.attachment_to_message_content was not implemented"
         )
 
-    def tag_to_message_content(
+    async def tag_to_message_content(
         self, tag: UserMessageTagContent
     ) -> ResponseInputContentParam:
         """
@@ -801,7 +800,7 @@ async def user_message_to_input(
 
             tag_content: ResponseInputMessageContentListParam = [
                 # should return summarized text items
-                self.tag_to_message_content(tag)
+                await self.tag_to_message_content(tag)
                 for tag in uniq_tags
             ]
 
diff --git a/docs/server.md b/docs/server.md
index e8625d6..c7df49a 100644
--- a/docs/server.md
+++ b/docs/server.md
@@ -323,7 +323,7 @@ class MyThreadConverter(ThreadItemConverter):
 
         # ..handle other attachment types
 
-    def hidden_context_to_input(self, item: HiddenContextItem) -> Message:
+    async def hidden_context_to_input(self, item: HiddenContextItem) -> Message:
         return Message(
             type="message",
             role="system",
@@ -335,7 +335,7 @@ class MyThreadConverter(ThreadItemConverter):
             ],
         )
 
-    def tag_to_message_content(self, tag: UserMessageTagContent):
+    async def tag_to_message_content(self, tag: UserMessageTagContent):
         tag_context = await retrieve_context_for_tag(tag.id)
         return ResponseInputTextParam(
             type="input_text",
diff --git a/tests/test_agents.py b/tests/test_agents.py
index c0fc4b0..ab9e9e6 100644
--- a/tests/test_agents.py
+++ b/tests/test_agents.py
@@ -469,7 +469,7 @@ async def test_input_item_converter_to_input_items_mixed():
 
 async def test_input_item_converter_user_input_with_tags():
     class MyThreadItemConverter(ThreadItemConverter):
-        def tag_to_message_content(self, tag):
+        async def tag_to_message_content(self, tag):
             return ResponseInputTextParam(
                 type="input_text", text=tag.text + " " + tag.data["key"]
             )