diff --git a/openapi.json b/openapi.json
index 75985c2..d322657 100644
--- a/openapi.json
+++ b/openapi.json
@@ -2612,7 +2612,6 @@
           }
         },
         "required": [
-          "role",
           "content"
         ],
         "additionalProperties": true
diff --git a/server/ap_server/models.py b/server/ap_server/models.py
index 964d257..47e1b31 100644
--- a/server/ap_server/models.py
+++ b/server/ap_server/models.py
@@ -301,7 +301,9 @@ class Message(BaseModel):
     model_config = ConfigDict(
         extra="allow",
     )
-    role: str = Field(..., description="The role of the message.", title="Role")
+    role: Optional[str] = Field(
+        None, description="The role of the message.", title="Role"
+    )
     content: Union[str, List[Union[Content, Content1]]] = Field(
         ..., description="The content of the message.", title="Content"
     )