diff --git a/llama_stack/providers/utils/inference/prompt_adapter.py b/llama_stack/providers/utils/inference/prompt_adapter.py
index e322adf35..2d66dc60b 100644
--- a/llama_stack/providers/utils/inference/prompt_adapter.py
+++ b/llama_stack/providers/utils/inference/prompt_adapter.py
@@ -358,17 +358,13 @@ def augment_messages_for_tools_llama_3_1(
 
     has_custom_tools = any(isinstance(dfn.tool_name, str) for dfn in request.tools)
     if has_custom_tools:
-        if (
-            request.tool_prompt_format == ToolPromptFormat.json
-            or request.tool_prompt_format is None
-        ):
+        fmt = request.tool_prompt_format or ToolPromptFormat.json
+        if fmt == ToolPromptFormat.json:
             tool_gen = JsonCustomToolGenerator()
-        elif request.tool_prompt_format == ToolPromptFormat.function_tag:
+        elif fmt == ToolPromptFormat.function_tag:
             tool_gen = FunctionTagCustomToolGenerator()
         else:
-            raise ValueError(
-                f"Non supported ToolPromptFormat {request.tool_prompt_format}"
-            )
+            raise ValueError(f"Non supported ToolPromptFormat {fmt}")
 
         custom_tools = [t for t in request.tools if isinstance(t.tool_name, str)]
         custom_template = tool_gen.gen(custom_tools)
@@ -413,10 +409,8 @@ def augment_messages_for_tools_llama_3_2(
 
     custom_tools = [dfn for dfn in request.tools if isinstance(dfn.tool_name, str)]
     if custom_tools:
-        if (
-            request.tool_prompt_format is not None
-            and request.tool_prompt_format != ToolPromptFormat.python_list
-        ):
+        fmt = request.tool_prompt_format or ToolPromptFormat.python_list
+        if fmt != ToolPromptFormat.python_list:
             raise ValueError(
                 f"Non supported ToolPromptFormat {request.tool_prompt_format}"
             )