fix: address review comments - unused import, FC+no-tools routing

- Remove unused asyncio import from test file
- Route FC-capable LLMs with no tools + response_model to
  _invoke_loop_native_no_tools (preserves structured output)
- FC-capable LLMs with no tools and no response_model still
  fall through to ReAct path (no regression)
- Add tests for both FC+no-tools routing scenarios

Co-Authored-By: João <joao@crewai.com>

lib/crewai/src/crewai/agents/crew_agent_executor.py

@@ -311,16 +311,21 @@ class CrewAgentExecutor(CrewAgentExecutorMixin):
             Final answer from the agent.
         """
         # Check if model supports native function calling
-        use_native_tools = (
+        supports_fc = (
             hasattr(self.llm, "supports_function_calling")
             and callable(getattr(self.llm, "supports_function_calling", None))
             and self.llm.supports_function_calling()
-            and self.original_tools
         )
 
-        if use_native_tools:
+        if supports_fc and self.original_tools:
             return self._invoke_loop_native_tools()
 
+        # FC-capable LLM with no tools but with response_model: use simple
+        # native call path which correctly passes response_model for structured
+        # output instead of dropping it in the ReAct path.
+        if supports_fc and not self.original_tools and self.response_model:
+            return self._invoke_loop_native_no_tools()
+
         # Fall back to ReAct text-based pattern
         return self._invoke_loop_react()
 
@@ -1132,16 +1137,21 @@ class CrewAgentExecutor(CrewAgentExecutorMixin):
             Final answer from the agent.
         """
         # Check if model supports native function calling
-        use_native_tools = (
+        supports_fc = (
             hasattr(self.llm, "supports_function_calling")
             and callable(getattr(self.llm, "supports_function_calling", None))
             and self.llm.supports_function_calling()
-            and self.original_tools
         )
 
-        if use_native_tools:
+        if supports_fc and self.original_tools:
             return await self._ainvoke_loop_native_tools()
 
+        # FC-capable LLM with no tools but with response_model: use simple
+        # native call path which correctly passes response_model for structured
+        # output instead of dropping it in the ReAct path.
+        if supports_fc and not self.original_tools and self.response_model:
+            return await self._ainvoke_loop_native_no_tools()
+
         # Fall back to ReAct text-based pattern
         return await self._ainvoke_loop_react()
 

lib/crewai/tests/agents/test_react_output_pydantic.py

@@ -13,7 +13,6 @@ conversion to pydantic/json should happen in task._export_output() after the ReA
 
 from __future__ import annotations
 
-import asyncio
 from typing import Any
 from unittest.mock import AsyncMock, MagicMock, patch
 
@@ -180,6 +179,52 @@ class TestReActFlowDoesNotPassResponseModel:
         mock_native.assert_called_once()
         mock_react.assert_not_called()
 
+    def test_invoke_loop_routes_to_native_no_tools_when_fc_no_tools_with_response_model(
+        self,
+    ) -> None:
+        """When LLM supports FC, has no tools, but HAS a response_model,
+        route to _invoke_loop_native_no_tools (which correctly passes
+        response_model) instead of falling through to the ReAct path."""
+        llm = _make_llm(supports_fc=True)
+        executor = _make_executor(llm, response_model=PersonInfo)
+        # No tools
+        executor.original_tools = []
+
+        with patch.object(
+            executor,
+            "_invoke_loop_native_no_tools",
+            return_value=AgentFinish(thought="done", output="test", text="Final Answer: test"),
+        ) as mock_native_no_tools:
+            with patch.object(executor, "_invoke_loop_react") as mock_react:
+                with patch.object(executor, "_invoke_loop_native_tools") as mock_native:
+                    executor._invoke_loop()
+
+        mock_native_no_tools.assert_called_once()
+        mock_react.assert_not_called()
+        mock_native.assert_not_called()
+
+    def test_invoke_loop_routes_to_react_when_fc_no_tools_no_response_model(
+        self,
+    ) -> None:
+        """When LLM supports FC, has no tools, and NO response_model,
+        fall through to ReAct path (no structured output to preserve)."""
+        llm = _make_llm(supports_fc=True)
+        executor = _make_executor(llm, response_model=None)
+        executor.original_tools = []
+
+        with patch.object(
+            executor,
+            "_invoke_loop_react",
+            return_value=AgentFinish(thought="done", output="test", text="Final Answer: test"),
+        ) as mock_react:
+            with patch.object(executor, "_invoke_loop_native_no_tools") as mock_native_no_tools:
+                with patch.object(executor, "_invoke_loop_native_tools") as mock_native:
+                    executor._invoke_loop()
+
+        mock_react.assert_called_once()
+        mock_native_no_tools.assert_not_called()
+        mock_native.assert_not_called()
+
     def test_react_flow_still_works_with_tool_usage(self) -> None:
         """Verify the ReAct loop still processes Action/Observation cycles
         correctly even when output_pydantic is set."""