diff --git a/src/dify_plugin/entities/tool.py b/src/dify_plugin/entities/tool.py
index 5fda0019..3bf34a71 100644
--- a/src/dify_plugin/entities/tool.py
+++ b/src/dify_plugin/entities/tool.py
@@ -359,7 +359,7 @@ def to_prompt_message(self) -> PromptMessageTool:
         for name, parameter in self.tool_parameters.items():
             tool.parameters[name] = {
                 "type": parameter.type.value,
-                "description": parameter.description,
+                "description": parameter.description or "",
             }
 
             if parameter.required:
diff --git a/src/dify_plugin/interfaces/agent/strategy.py b/src/dify_plugin/interfaces/agent/strategy.py
index 9d20bdef..eed44d29 100644
--- a/src/dify_plugin/interfaces/agent/strategy.py
+++ b/src/dify_plugin/interfaces/agent/strategy.py
@@ -302,7 +302,7 @@ def _convert_tool_to_prompt_message_tool(
         """Convert tool to prompt message tool"""
         message_tool = PromptMessageTool(
             name=tool.identity.name,
-            description=tool.description.llm if tool.description else "",
+            description=(tool.description.llm or "") if tool.description else "",
             parameters={
                 "type": "object",
                 "properties": {},
diff --git a/src/dify_plugin/interfaces/model/openai_compatible/llm.py b/src/dify_plugin/interfaces/model/openai_compatible/llm.py
index c5a1f46f..6b7a1d9a 100644
--- a/src/dify_plugin/interfaces/model/openai_compatible/llm.py
+++ b/src/dify_plugin/interfaces/model/openai_compatible/llm.py
@@ -598,7 +598,7 @@ def _generate(
                 data["functions"] = [
                     {
                         "name": tool.name,
-                        "description": tool.description,
+                        "description": tool.description or "",
                         "parameters": tool.parameters,
                     }
                     for tool in tools
@@ -1127,7 +1127,7 @@ def _num_tokens_for_tools(self, tools: list[PromptMessageTool]) -> int:
                 num_tokens += self._get_num_tokens_by_gpt2(tool.name)
             num_tokens += self._get_num_tokens_by_gpt2("description")
             if hasattr(tool, "description"):
-                num_tokens += self._get_num_tokens_by_gpt2(tool.description)
+                num_tokens += self._get_num_tokens_by_gpt2(tool.description or "")
             if hasattr(tool, "parameters"):
                 parameters = tool.parameters
                 num_tokens += self._get_num_tokens_by_gpt2("parameters")