Fix issue #2738: Exclude stop parameter for o3 model

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

src/crewai/llm.py

@@ -351,7 +351,6 @@ class LLM(BaseLLM):
             "temperature": self.temperature,
             "top_p": self.top_p,
             "n": self.n,
-            "stop": self.stop,
             "max_tokens": self.max_tokens or self.max_completion_tokens,
             "presence_penalty": self.presence_penalty,
             "frequency_penalty": self.frequency_penalty,
@@ -369,6 +368,9 @@ class LLM(BaseLLM):
             "reasoning_effort": self.reasoning_effort,
             **self.additional_params,
         }
+        
+        if self.stop and self.supports_stop_words():
+            params["stop"] = self.stop
 
         # Remove None values from params
         return {k: v for k, v in params.items() if v is not None}

tests/unit/test_llm.py

@@ -0,0 +1,52 @@
+import unittest
+from unittest.mock import patch, MagicMock
+from types import SimpleNamespace
+
+from crewai.llm import LLM
+
+
+class TestLLM(unittest.TestCase):
+    @patch("crewai.llm.litellm.completion")
+    @patch("crewai.llm.LLM.supports_stop_words")
+    def test_call_with_supported_stop_words(self, mock_supports_stop_words, mock_completion):
+        mock_supports_stop_words.return_value = True
+        
+        message = SimpleNamespace(content="Hello, World!")
+        choice = SimpleNamespace(message=message)
+        response = SimpleNamespace(choices=[choice])
+        mock_completion.return_value = response
+        
+        llm = LLM(model="gpt-4", stop=["STOP"])
+        
+        messages = [{"role": "user", "content": "Say Hello"}]
+        result = llm.call(messages)
+        
+        mock_completion.assert_called_once()
+        call_args = mock_completion.call_args[1]
+        self.assertIn("stop", call_args)
+        self.assertEqual(call_args["stop"], ["STOP"])
+        self.assertEqual(result, "Hello, World!")
+    
+    @patch("crewai.llm.litellm.completion")
+    @patch("crewai.llm.LLM.supports_stop_words")
+    def test_call_with_unsupported_stop_words(self, mock_supports_stop_words, mock_completion):
+        mock_supports_stop_words.return_value = False
+        
+        message = SimpleNamespace(content="Hello, World!")
+        choice = SimpleNamespace(message=message)
+        response = SimpleNamespace(choices=[choice])
+        mock_completion.return_value = response
+        
+        llm = LLM(model="o3", stop=["STOP"])
+        
+        messages = [{"role": "user", "content": "Say Hello"}]
+        result = llm.call(messages)
+        
+        mock_completion.assert_called_once()
+        call_args = mock_completion.call_args[1]
+        self.assertNotIn("stop", call_args)
+        self.assertEqual(result, "Hello, World!")
+
+
+if __name__ == "__main__":
+    unittest.main()