diff --git a/python/sglang/srt/function_call/qwen3_coder_detector.py b/python/sglang/srt/function_call/qwen3_coder_detector.py
index 674a189a7..454f5048e 100644
--- a/python/sglang/srt/function_call/qwen3_coder_detector.py
+++ b/python/sglang/srt/function_call/qwen3_coder_detector.py
@@ -57,6 +57,15 @@ class Qwen3CoderDetector(BaseFormatDetector):
         )
         self._buf: str = ""
 
+        # Streaming state variables
+        self._current_function_name: str = ""
+        self._current_parameters: Dict[str, Any] = {}
+        self._streamed_parameters: Dict[str, str] = (
+            {}
+        )  # Track what parameter content we've streamed
+        self._in_tool_call: bool = False
+        self._function_name_sent: bool = False
+
     def has_tool_call(self, text: str) -> bool:
         return self.tool_call_start_token in text
 
@@ -70,23 +79,224 @@ class Qwen3CoderDetector(BaseFormatDetector):
         self._buf += new_text
         normal = ""
         calls: List[ToolCallItem] = []
+
+        # Build tool indices for validation
+        if not hasattr(self, "_tool_indices"):
+            self._tool_indices = self._get_tool_indices(tools)
+
         while True:
-            if self.tool_call_start_token not in self._buf:
+            # If we're not in a tool call and don't see a start token, return normal text
+            if not self._in_tool_call and self.tool_call_start_token not in self._buf:
                 normal += self._buf
                 self._buf = ""
                 break
-            s = self._buf.find(self.tool_call_start_token)
-            if s > 0:
+
+            # Look for tool call start
+            if not self._in_tool_call:
+                s = self._buf.find(self.tool_call_start_token)
+                if s == -1:
+                    normal += self._buf
+                    self._buf = ""
+                    break
+
                 normal += self._buf[:s]
                 self._buf = self._buf[s:]
-            e = self._buf.find(self.tool_call_end_token)
-            if e == -1:
-                break
-            block = self._buf[: e + len(self.tool_call_end_token)]
-            self._buf = self._buf[e + len(self.tool_call_end_token) :]
-            calls.extend(self._parse_block(block, tools))
+
+                self._in_tool_call = True
+                self._function_name_sent = False
+                self._current_function_name = ""
+                self._current_parameters = {}
+                self._streamed_parameters = {}
+
+                # Remove the start token
+                self._buf = self._buf[len(self.tool_call_start_token) :]
+                continue
+
+            # We're in a tool call, try to parse function name if not sent yet
+            if not self._function_name_sent:
+                # Look for function name pattern: <function=name>
+                function_match = re.search(r"<function=([^>]+)>", self._buf)
+                if function_match:
+                    function_name = function_match.group(1).strip()
+
+                    # Validate function name
+                    if function_name in self._tool_indices:
+                        self._current_function_name = function_name
+                        self._function_name_sent = True
+
+                        # Initialize tool call tracking
+                        if self.current_tool_id == -1:
+                            self.current_tool_id = 0
+
+                        # Ensure tracking arrays are large enough
+                        while len(self.prev_tool_call_arr) <= self.current_tool_id:
+                            self.prev_tool_call_arr.append({})
+                        while len(self.streamed_args_for_tool) <= self.current_tool_id:
+                            self.streamed_args_for_tool.append("")
+
+                        # Store tool call info
+                        self.prev_tool_call_arr[self.current_tool_id] = {
+                            "name": function_name,
+                            "arguments": {},
+                        }
+
+                        # Send tool name with empty parameters
+                        calls.append(
+                            ToolCallItem(
+                                tool_index=self.current_tool_id,
+                                name=function_name,
+                                parameters="",
+                            )
+                        )
+
+                        # Remove the processed function declaration
+                        self._buf = self._buf[function_match.end() :]
+                        continue
+                    else:
+                        # Invalid function name, reset state
+                        logger.warning(f"Invalid function name: {function_name}")
+                        self._reset_streaming_state()
+                        normal += self._buf
+                        self._buf = ""
+                        break
+                else:
+                    # Function name not complete yet, wait for more text
+                    break
+
+            # Parse parameters incrementally
+            if self._function_name_sent:
+                # Process parameters and get any calls to emit
+                parameter_calls = self._parse_and_stream_parameters(self._buf)
+                calls.extend(parameter_calls)
+
+                # Check if tool call is complete
+                if self.tool_call_end_token in self._buf:
+                    end_pos = self._buf.find(self.tool_call_end_token)
+
+                    # Add closing brace to complete the JSON object
+                    current_streamed = self.streamed_args_for_tool[self.current_tool_id]
+                    if current_streamed:
+                        # Count opening and closing braces to check if JSON is complete
+                        open_braces = current_streamed.count("{")
+                        close_braces = current_streamed.count("}")
+                        if open_braces > close_braces:
+                            calls.append(
+                                ToolCallItem(
+                                    tool_index=self.current_tool_id,
+                                    name=None,
+                                    parameters="}",
+                                )
+                            )
+                            self.streamed_args_for_tool[self.current_tool_id] = (
+                                current_streamed + "}"
+                            )
+
+                    # Complete the tool call
+                    self._buf = self._buf[end_pos + len(self.tool_call_end_token) :]
+                    self._reset_streaming_state()
+                    self.current_tool_id += 1
+                    continue
+                else:
+                    # Tool call not complete yet, wait for more text
+                    break
+
         return StreamingParseResult(normal_text=normal, calls=calls)
 
+    def _parse_and_stream_parameters(self, text_to_parse: str) -> List[ToolCallItem]:
+        """
+        Parse complete parameter blocks from text and return any tool call items to emit.
+
+        This method:
+        1. Finds all complete <parameter> blocks
+        2. Parses them into a dictionary
+        3. Compares with current parameters and generates diff if needed
+        4. Updates internal state
+
+        Args:
+            text_to_parse: The text to search for parameter blocks
+
+        Returns:
+            List of ToolCallItem objects to emit (may be empty)
+        """
+        calls: List[ToolCallItem] = []
+
+        # Find all complete parameter patterns
+        param_matches = list(
+            re.finditer(
+                r"<parameter=([^>]+)>(.*?)</parameter>", text_to_parse, re.DOTALL
+            )
+        )
+
+        # Build new parameters dictionary
+        new_params = {}
+        for match in param_matches:
+            param_name = match.group(1).strip()
+            param_value = match.group(2)
+            new_params[param_name] = _safe_val(param_value)
+
+        # Calculate parameter diff to stream with proper incremental JSON building
+        if new_params != self._current_parameters:
+            previous_args_json = self.streamed_args_for_tool[self.current_tool_id]
+
+            # Build incremental JSON properly
+            if not self._current_parameters:
+                # First parameter(s) - start JSON object but don't close it yet
+                items = []
+                for key, value in new_params.items():
+                    items.append(
+                        f"{json.dumps(key, ensure_ascii=False)}: {json.dumps(value, ensure_ascii=False)}"
+                    )
+                json_fragment = "{" + ", ".join(items)
+
+                calls.append(
+                    ToolCallItem(
+                        tool_index=self.current_tool_id,
+                        name=None,
+                        parameters=json_fragment,
+                    )
+                )
+                self.streamed_args_for_tool[self.current_tool_id] = json_fragment
+
+            else:
+                # Additional parameters - add them incrementally
+                new_keys = set(new_params.keys()) - set(self._current_parameters.keys())
+                if new_keys:
+                    # Build the continuation part (no closing brace yet)
+                    continuation_parts = []
+                    for key in new_keys:
+                        value = new_params[key]
+                        continuation_parts.append(
+                            f"{json.dumps(key, ensure_ascii=False)}: {json.dumps(value, ensure_ascii=False)}"
+                        )
+
+                    json_fragment = ", " + ", ".join(continuation_parts)
+
+                    calls.append(
+                        ToolCallItem(
+                            tool_index=self.current_tool_id,
+                            name=None,
+                            parameters=json_fragment,
+                        )
+                    )
+                    self.streamed_args_for_tool[self.current_tool_id] = (
+                        previous_args_json + json_fragment
+                    )
+
+            # Update current state
+            self._current_parameters = new_params
+            self.prev_tool_call_arr[self.current_tool_id]["arguments"] = new_params
+
+        return calls
+
+    def _reset_streaming_state(self):
+        """Reset streaming state for the next tool call"""
+        self._in_tool_call = False
+        self._function_name_sent = False
+        self._current_function_name = ""
+        self._current_parameters = {}
+        self._streamed_parameters = {}
+        self.current_tool_name_sent = False
+
     def _extract(self, text: str, tools: List[Tool]) -> Tuple[str, List[ToolCallItem]]:
         normal_parts: List[str] = []
         calls: List[ToolCallItem] = []
diff --git a/test/srt/test_function_call_parser.py b/test/srt/test_function_call_parser.py
index cc4521622..afbba82e3 100644
--- a/test/srt/test_function_call_parser.py
+++ b/test/srt/test_function_call_parser.py
@@ -1707,17 +1707,37 @@ fahrenheit
 
         accumulated_text = ""
         accumulated_calls = []
+        tool_calls_by_index = {}
 
         for chunk in chunks:
             result = self.detector.parse_streaming_increment(chunk, tools=self.tools)
             accumulated_text += result.normal_text
-            accumulated_calls.extend(result.calls)
+
+            # Track calls by tool_index to handle streaming properly
+            for call in result.calls:
+                if call.tool_index is not None:
+                    if call.tool_index not in tool_calls_by_index:
+                        tool_calls_by_index[call.tool_index] = {
+                            "name": "",
+                            "parameters": "",
+                        }
+
+                    if call.name:
+                        tool_calls_by_index[call.tool_index]["name"] = call.name
+                    if call.parameters:
+                        tool_calls_by_index[call.tool_index][
+                            "parameters"
+                        ] += call.parameters
 
         self.assertEqual(accumulated_text, "Sure! Let me check the weather.")
-        self.assertEqual(len(accumulated_calls), 1)
-        self.assertEqual(accumulated_calls[0].name, "get_current_weather")
+        self.assertEqual(len(tool_calls_by_index), 1)
 
-        params = json.loads(accumulated_calls[0].parameters)
+        # Get the complete tool call
+        tool_call = tool_calls_by_index[0]
+        self.assertEqual(tool_call["name"], "get_current_weather")
+
+        # Parse the accumulated parameters
+        params = json.loads(tool_call["parameters"])
         self.assertEqual(params["city"], "Dallas")
         self.assertEqual(params["state"], "TX")
 
@@ -1735,20 +1755,49 @@ fahrenheit
             # Missing </parameter>, </function>, </tool_call>
         ]
 
-        accumulated_calls = []
+        tool_calls_by_index = {}
         for chunk in chunks:
             result = self.detector.parse_streaming_increment(chunk, tools=self.tools)
-            accumulated_calls.extend(result.calls)
 
-        # Should not have any complete calls yet
-        self.assertEqual(len(accumulated_calls), 0)
+            # Track calls by tool_index to handle streaming properly
+            for call in result.calls:
+                if call.tool_index is not None:
+                    if call.tool_index not in tool_calls_by_index:
+                        tool_calls_by_index[call.tool_index] = {
+                            "name": "",
+                            "parameters": "",
+                        }
+
+                    if call.name:
+                        tool_calls_by_index[call.tool_index]["name"] = call.name
+                    if call.parameters:
+                        tool_calls_by_index[call.tool_index][
+                            "parameters"
+                        ] += call.parameters
+
+        # Should have partial tool call with name but incomplete parameters
+        self.assertGreater(len(tool_calls_by_index), 0)
+        self.assertEqual(tool_calls_by_index[0]["name"], "get_current_weather")
+
+        # Parameters should be incomplete (no closing brace)
+        params_str = tool_calls_by_index[0]["parameters"]
+        self.assertTrue(params_str.startswith('{"city": "Dallas"'))
+        self.assertFalse(params_str.endswith("}"))
 
         # Now complete it
         result = self.detector.parse_streaming_increment(
             "\n</parameter>\n</function>\n</tool_call>", tools=self.tools
         )
-        self.assertEqual(len(result.calls), 1)
-        self.assertEqual(result.calls[0].name, "get_current_weather")
+
+        # Update the accumulated parameters
+        for call in result.calls:
+            if call.tool_index is not None and call.parameters:
+                tool_calls_by_index[call.tool_index]["parameters"] += call.parameters
+
+        # Now should have complete parameters
+        final_params = json.loads(tool_calls_by_index[0]["parameters"])
+        self.assertEqual(final_params["city"], "Dallas")
+        self.assertEqual(final_params["state"], "TX")
 
     def test_edge_case_no_parameters(self):
         """Test tool call without parameters."""
@@ -1845,15 +1894,15 @@ hello world
     def test_parse_streaming_incremental(self):
         """Test that streaming is truly incremental with very small chunks."""
         model_output = """I'll check the weather.<tool_call>
-<function=get_current_weather>
-<parameter=city>
-Dallas
-</parameter>
-<parameter=state>
-TX
-</parameter>
-</function>
-</tool_call>"""
+        <function=get_current_weather>
+        <parameter=city>
+        Dallas
+        </parameter>
+        <parameter=state>
+        TX
+        </parameter>
+        </function>
+        </tool_call>"""
 
         # Simulate more realistic token-based chunks where <tool_call> is a single token
         chunks = [
@@ -1871,49 +1920,59 @@ TX
         ]
 
         accumulated_text = ""
-        accumulated_calls = []
+        tool_calls = []
         chunks_count = 0
 
         for chunk in chunks:
-            result = self.detector.parse_streaming_increment(chunk, tools=self.tools)
+            result = self.detector.parse_streaming_increment(chunk, self.tools)
             accumulated_text += result.normal_text
-            accumulated_calls.extend(result.calls)
             chunks_count += 1
+            for tool_call_chunk in result.calls:
+                if (
+                    hasattr(tool_call_chunk, "tool_index")
+                    and tool_call_chunk.tool_index is not None
+                ):
+                    while len(tool_calls) <= tool_call_chunk.tool_index:
+                        tool_calls.append({"name": "", "parameters": ""})
+                    tc = tool_calls[tool_call_chunk.tool_index]
+                    if tool_call_chunk.name:
+                        tc["name"] = tool_call_chunk.name
+                    if tool_call_chunk.parameters:
+                        tc["parameters"] += tool_call_chunk.parameters
 
         self.assertGreater(chunks_count, 3)
 
         # Verify the accumulated results
         self.assertIn("I'll check the weather.", accumulated_text)
-        self.assertEqual(len(accumulated_calls), 1)
-        self.assertEqual(accumulated_calls[0].name, "get_current_weather")
+        self.assertEqual(len(tool_calls), 1)
+        self.assertEqual(tool_calls[0]["name"], "get_current_weather")
 
-        params = json.loads(accumulated_calls[0].parameters)
-        self.assertEqual(params["city"], "Dallas")
-        self.assertEqual(params["state"], "TX")
+        params = json.loads(tool_calls[0]["parameters"])
+        self.assertEqual(params, {"city": "Dallas", "state": "TX"})
 
     def test_parse_streaming_multiple_tools(self):
         """Test streaming with multiple tool calls."""
         model_output = """<tool_call>
-<function=get_current_weather>
-<parameter=city>
-Dallas
-</parameter>
-<parameter=state>
-TX
-</parameter>
-</function>
-</tool_call>
-Some text in between.
-<tool_call>
-<function=calculate_area>
-<parameter=shape>
-circle
-</parameter>
-<parameter=dimensions>
-{"radius": 5}
-</parameter>
-</function>
-</tool_call>"""
+        <function=get_current_weather>
+        <parameter=city>
+        Dallas
+        </parameter>
+        <parameter=state>
+        TX
+        </parameter>
+        </function>
+        </tool_call>
+        Some text in between.
+        <tool_call>
+        <function=calculate_area>
+        <parameter=shape>
+        circle
+        </parameter>
+        <parameter=dimensions>
+        {"radius": 5}
+        </parameter>
+        </function>
+        </tool_call>"""
 
         # Simulate streaming by chunks
         chunk_size = 20
@@ -1923,25 +1982,37 @@ circle
         ]
 
         accumulated_text = ""
-        accumulated_calls = []
+        tool_calls = []
+        chunks_count = 0
 
         for chunk in chunks:
-            result = self.detector.parse_streaming_increment(chunk, tools=self.tools)
+            result = self.detector.parse_streaming_increment(chunk, self.tools)
             accumulated_text += result.normal_text
-            accumulated_calls.extend(result.calls)
+            chunks_count += 1
+            for tool_call_chunk in result.calls:
+                if (
+                    hasattr(tool_call_chunk, "tool_index")
+                    and tool_call_chunk.tool_index is not None
+                ):
+                    while len(tool_calls) <= tool_call_chunk.tool_index:
+                        tool_calls.append({"name": "", "parameters": ""})
+                    tc = tool_calls[tool_call_chunk.tool_index]
+                    if tool_call_chunk.name:
+                        tc["name"] = tool_call_chunk.name
+                    if tool_call_chunk.parameters:
+                        tc["parameters"] += tool_call_chunk.parameters
 
         self.assertIn("Some text in between.", accumulated_text)
-        self.assertEqual(len(accumulated_calls), 2)
-        self.assertEqual(accumulated_calls[0].name, "get_current_weather")
-        self.assertEqual(accumulated_calls[1].name, "calculate_area")
+        self.assertEqual(len(tool_calls), 2)
+        self.assertEqual(tool_calls[0]["name"], "get_current_weather")
+        self.assertEqual(tool_calls[1]["name"], "calculate_area")
 
         # Verify parameters
-        params1 = json.loads(accumulated_calls[0].parameters)
-        self.assertEqual(params1["city"], "Dallas")
+        params1 = json.loads(tool_calls[0]["parameters"])
+        self.assertEqual(params1, {"city": "Dallas", "state": "TX"})
 
-        params2 = json.loads(accumulated_calls[1].parameters)
-        self.assertEqual(params2["shape"], "circle")
-        self.assertEqual(params2["dimensions"], {"radius": 5})
+        params2 = json.loads(tool_calls[1]["parameters"])
+        self.assertEqual(params2, {"shape": "circle", "dimensions": {"radius": 5}})
 
 
 class TestGlm4MoeDetector(unittest.TestCase):