diff --git a/agent/modules.py b/agent/modules.py
index c6c1590..5660821 100644
--- a/agent/modules.py
+++ b/agent/modules.py
@@ -1,6 +1,6 @@
 import dspy
 from enum import Enum
-from typing import Any, Dict, List, Optional, Literal
+from typing import Any, Dict, List, Optional, Literal, Union, get_origin
 from pydantic import BaseModel, Field, ValidationError
 
 class FieldType(str, Enum):
@@ -80,8 +80,8 @@ class PydanticModelSchema(BaseModel):
         else:
             type_annotation = field_def.type.value
 
-        # Add Optional wrapper if not required
-        if not field_def.required:
+        # Add Optional wrapper if not required (but avoid double-wrapping)
+        if not field_def.required and not type_annotation.startswith("Optional["):
             type_annotation = f"Optional[{type_annotation}]"
 
         # Build Field() arguments
@@ -331,8 +331,9 @@ class SignatureGenerator(dspy.Module):
                 }
                 py_type = type_map.get(type_str, str)
 
-            # Wrap in Optional if not required
-            if not field_def.required and not isinstance(py_type, type(Optional[str])):
+            # Wrap in Optional if not required (but avoid double-wrapping)
+            # Optional[X] is Union[X, None], so check if already a Union type
+            if not field_def.required and get_origin(py_type) is not Union:
                 py_type = Optional[py_type]
 
             # Create Pydantic field