diff --git a/ollama/_types.py b/ollama/_types.py
index 653e122..3b2452e 100644
--- a/ollama/_types.py
+++ b/ollama/_types.py
@@ -4,6 +4,7 @@ from pathlib import Path
 from datetime import datetime
 from typing import (
   Any,
+  List,
   Literal,
   Mapping,
   Optional,
@@ -229,7 +230,7 @@ class Tool(SubscriptableBaseModel):
     description: str
 
     class Parameters(SubscriptableBaseModel):
-      type: str
+      type: Union[str, List[str]]
       required: Optional[Sequence[str]] = None
       properties: Optional[JsonSchemaValue] = None
 
diff --git a/ollama/_utils.py b/ollama/_utils.py
index f4d14a0..b3de43f 100644
--- a/ollama/_utils.py
+++ b/ollama/_utils.py
@@ -1,7 +1,5 @@
 from typing import Any, Callable, Dict, List, Mapping, Optional, Sequence, Union, get_args, get_origin
 from ollama._types import Tool
-from icecream import ic
-
 
 PYTHON_TO_JSON_TYPES = {
   str: 'string',
@@ -16,18 +14,27 @@ PYTHON_TO_JSON_TYPES = {
 }
 
 
-def _get_json_type(python_type: Any) -> str:
+def _get_json_type(python_type: Any) -> str | list[str]:
   """Convert Python type to JSON schema type."""
-  # Handle Optional types (Union[type, None])
+  # Handle Optional types (Union[type, None] and type | None)
   origin = get_origin(python_type)
   if origin is Union:
     print('python_type', python_type)
     args = get_args(python_type)
-    if len(args) == 2 and args[1] is type(None):  # Optional case
-      return _get_json_type(args[0])
+    # Filter out None/NoneType from union args
+    non_none_args = [arg for arg in args if arg not in (None, type(None))]
+    non_none_args_types = [PYTHON_TO_JSON_TYPES[arg] for arg in non_none_args]
+    if non_none_args:
+      if len(non_none_args) == 1:
+        return _get_json_type(non_none_args[0])
+      else:
+        return non_none_args_types
+
+    return 'null'
 
   # Get basic type mapping
   if python_type in PYTHON_TO_JSON_TYPES:
+    print('python_type', python_type, PYTHON_TO_JSON_TYPES[python_type])
     return PYTHON_TO_JSON_TYPES[python_type]
 
   # Handle typing.List, typing.Dict etc.
@@ -38,6 +45,15 @@ def _get_json_type(python_type: Any) -> str:
   return 'string'
 
 
+def _is_optional_type(python_type: Any) -> bool:
+  """Check if a type is optional (can be None)."""
+  origin = get_origin(python_type)
+  if origin is Union:
+    args = get_args(python_type)
+    return any(arg in (None, type(None)) for arg in args)
+  return False
+
+
 def convert_function_to_tool(func: Callable) -> Tool:
   doc_string = func.__doc__
   if not doc_string:
@@ -85,7 +101,10 @@ def convert_function_to_tool(func: Callable) -> Tool:
       'type': _get_json_type(param_type),
       'description': param_desc,
     }
-    parameters['required'].append(param_name)
+
+    # Only add to required if not optional
+    if not _is_optional_type(param_type):
+      parameters['required'].append(param_name)
 
   tool_dict = {
     'type': 'function',
@@ -95,7 +114,6 @@ def convert_function_to_tool(func: Callable) -> Tool:
       'parameters': parameters,
     },
   }
-  print('descs', tool_dict['function']['description'])
   return Tool.model_validate(tool_dict)
 
 
@@ -111,7 +129,6 @@ def process_tools(tools: Optional[Sequence[Union[Mapping[str, Any], Tool, Callab
   for tool in tools:
     if callable(tool):
       processed_tools.append(convert_function_to_tool(tool))
-      ic('processed tool', processed_tools[-1].model_dump())
     else:
       # Existing tool handling logic
       processed_tools.append(Tool.model_validate(tool))