diff --git a/backend/open_webui/main.py b/backend/open_webui/main.py
index 17340427c..35f707328 100644
--- a/backend/open_webui/main.py
+++ b/backend/open_webui/main.py
@@ -439,10 +439,17 @@ async def chat_completion_tools_handler(
             tool_function_params = result.get("parameters", {})
 
             try:
+                required_params = (
+                    tools[tool_function_name]
+                    .get("spec", {})
+                    .get("parameters", {})
+                    .get("required", [])
+                )
                 tool_function = tools[tool_function_name]["callable"]
-                sig = inspect.signature(tool_function)
                 tool_function_params = {
-                    k: v for k, v in tool_function_params.items() if k in sig.parameters
+                    k: v
+                    for k, v in tool_function_params.items()
+                    if k in required_params
                 }
                 tool_output = await tool_function(**tool_function_params)