[Bugfix] fix Qwen3.5 tool calling bug (#36774)

Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>

vllm/tool_parsers/qwen3coder_tool_parser.py

@@ -249,7 +249,10 @@ class Qwen3CoderToolParser(ToolParser):
         self, function_call_str: str, tools: list[ChatCompletionToolsParam] | None
     ) -> ToolCall | None:
         # Extract function name
-        end_index = function_call_str.index(">")
+        end_index = function_call_str.find(">")
+        # If there's no ">" character, this is not a valid xml function call
+        if end_index == -1:
+            return None
         function_name = function_call_str[:end_index]
         param_config = self._get_arguments_config(function_name, tools)
         parameters = function_call_str[end_index + 1 :]
@@ -316,7 +319,6 @@ class Qwen3CoderToolParser(ToolParser):
                 self._parse_xml_function_call(function_call_str, request.tools)
                 for function_call_str in function_calls
             ]
-
             # Populate prev_tool_call_arr for serving layer to set finish_reason
             self.prev_tool_call_arr.clear()  # Clear previous calls
             for tool_call in tool_calls:
@@ -333,10 +335,10 @@ class Qwen3CoderToolParser(ToolParser):
             idx = model_output.find(self.tool_call_prefix)
             content_index = content_index if content_index >= 0 else idx
             content = model_output[:content_index]  # .rstrip()
-
+            valid_tool_calls = [tc for tc in tool_calls if tc is not None]
             return ExtractedToolCallInformation(
-                tools_called=(len(tool_calls) > 0),
-                tool_calls=tool_calls,
+                tools_called=(len(valid_tool_calls) > 0),
+                tool_calls=valid_tool_calls,
                 content=content if content else None,
             )