Fix Gemini model integration issues (#2803)

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

src/crewai/llm.py

@@ -322,6 +322,42 @@ class LLM(BaseLLM):
         ANTHROPIC_PREFIXES = ("anthropic/", "claude-", "claude/")
         return any(prefix in model.lower() for prefix in ANTHROPIC_PREFIXES)
 
+    def _is_gemini_model(self, model: str) -> bool:
+        """Determine if the model is from Google Gemini provider.
+
+        Args:
+            model: The model identifier string.
+
+        Returns:
+            bool: True if the model is from Gemini, False otherwise.
+        """
+        GEMINI_IDENTIFIERS = ("gemini", "gemma-")
+        return any(identifier in model.lower() for identifier in GEMINI_IDENTIFIERS)
+
+    def _normalize_gemini_model(self, model: str) -> str:
+        """Normalize Gemini model name to the format expected by LiteLLM.
+        
+        Handles formats like "models/gemini-pro" or "gemini-pro" and converts
+        them to "gemini/gemini-pro" format.
+
+        Args:
+            model: The model identifier string.
+
+        Returns:
+            str: Normalized model name.
+        """
+        if model.startswith("gemini/"):
+            return model
+            
+        if model.startswith("models/"):
+            model_name = model.split("/", 1)[1]
+            return f"gemini/{model_name}"
+            
+        if self._is_gemini_model(model) and "/" not in model:
+            return f"gemini/{model}"
+            
+        return model
+
     def _prepare_completion_params(
         self,
         messages: Union[str, List[Dict[str, str]]],
@@ -343,9 +379,18 @@ class LLM(BaseLLM):
             messages = [{"role": "user", "content": messages}]
         formatted_messages = self._format_messages_for_provider(messages)
 
-        # --- 2) Prepare the parameters for the completion call
+        model = self.model
+        if self._is_gemini_model(model):
+            model = self._normalize_gemini_model(model)
+            
+            # --- 2.1) Map GOOGLE_API_KEY to GEMINI_API_KEY if needed
+            if not os.environ.get("GEMINI_API_KEY") and os.environ.get("GOOGLE_API_KEY"):
+                os.environ["GEMINI_API_KEY"] = os.environ["GOOGLE_API_KEY"]
+                logging.info("Mapped GOOGLE_API_KEY to GEMINI_API_KEY for Gemini model")
+
+        # --- 3) Prepare the parameters for the completion call
         params = {
-            "model": self.model,
+            "model": model,
             "messages": formatted_messages,
             "timeout": self.timeout,
             "temperature": self.temperature,