diff --git a/src/crewai/llm.py b/src/crewai/llm.py
index c1e52f2cd..69780af8c 100644
--- a/src/crewai/llm.py
+++ b/src/crewai/llm.py
@@ -231,7 +231,7 @@ class LLM:
         :return: Final text response from the LLM or the tool result
         """
         with suppress_warnings():
-            if callbacks:
+            if callbacks and len(callbacks) > 0:
                 self.set_callbacks(callbacks)
 
             try:
@@ -259,7 +259,6 @@ class LLM:
                     "tools": tools,  # pass the tool schema
                 }
 
-                # Remove None values
                 params = {k: v for k, v in params.items() if v is not None}
 
                 response = litellm.completion(**params)
@@ -290,8 +289,6 @@ class LLM:
                         # Call the actual tool function
                         result = fn(**function_args)
 
-                        print(f"Result from function '{function_name}': {result}")
-
                         # Return the result directly
                         return result
 
@@ -368,20 +365,36 @@ class LLM:
     def set_env_callbacks(self):
         """
         Sets the success and failure callbacks for the LiteLLM library from environment variables.
+
+        This method reads the `LITELLM_SUCCESS_CALLBACKS` and `LITELLM_FAILURE_CALLBACKS`
+        environment variables, which should contain comma-separated lists of callback names.
+        It then assigns these lists to `litellm.success_callback` and `litellm.failure_callback`,
+        respectively.
+
+        If the environment variables are not set or are empty, the corresponding callback lists
+        will be set to empty lists.
+
+        Example:
+            LITELLM_SUCCESS_CALLBACKS="langfuse,langsmith"
+            LITELLM_FAILURE_CALLBACKS="langfuse"
+
+        This will set `litellm.success_callback` to ["langfuse", "langsmith"] and
+        `litellm.failure_callback` to ["langfuse"].
         """
-        success_callbacks_str = os.environ.get("LITELLM_SUCCESS_CALLBACKS", "")
-        success_callbacks = []
-        if success_callbacks_str:
-            success_callbacks = [
-                cb.strip() for cb in success_callbacks_str.split(",") if cb.strip()
-            ]
+        with suppress_warnings():
+            success_callbacks_str = os.environ.get("LITELLM_SUCCESS_CALLBACKS", "")
+            success_callbacks = []
+            if success_callbacks_str:
+                success_callbacks = [
+                    cb.strip() for cb in success_callbacks_str.split(",") if cb.strip()
+                ]
 
-        failure_callbacks_str = os.environ.get("LITELLM_FAILURE_CALLBACKS", "")
-        failure_callbacks = []
-        if failure_callbacks_str:
-            failure_callbacks = [
-                cb.strip() for cb in failure_callbacks_str.split(",") if cb.strip()
-            ]
+            failure_callbacks_str = os.environ.get("LITELLM_FAILURE_CALLBACKS", "")
+            failure_callbacks = []
+            if failure_callbacks_str:
+                failure_callbacks = [
+                    cb.strip() for cb in failure_callbacks_str.split(",") if cb.strip()
+                ]
 
-            litellm.success_callback = success_callbacks
-            litellm.failure_callback = failure_callbacks
+                litellm.success_callback = success_callbacks
+                litellm.failure_callback = failure_callbacks
diff --git a/src/crewai/utilities/llm_utils.py b/src/crewai/utilities/llm_utils.py
index a15b1417f..ea1783fa9 100644
--- a/src/crewai/utilities/llm_utils.py
+++ b/src/crewai/utilities/llm_utils.py
@@ -171,21 +171,25 @@ def _llm_via_environment_or_fallback() -> Optional[LLM]:
     set_provider = model_name.split("/")[0] if "/" in model_name else "openai"
 
     if set_provider in ENV_VARS:
-        for env_var in ENV_VARS[set_provider]:
-            key_name = env_var.get("key_name")
-            if key_name and key_name not in UNACCEPTED_ATTRIBUTES:
-                env_value = os.environ.get(key_name)
-                if env_value:
-                    # Map environment variable names to recognized parameters
-                    param_key = _normalize_key_name(key_name.lower())
-                    llm_params[param_key] = env_value
-            elif isinstance(env_var, dict):
-                if env_var.get("default", False):
-                    for key, value in env_var.items():
-                        if key not in ["prompt", "key_name", "default"]:
-                            llm_params[key.lower()] = value
-            else:
-                print(f"Expected env_var to be a dictionary, but got {type(env_var)}")
+        env_vars_for_provider = ENV_VARS[set_provider]
+        if isinstance(env_vars_for_provider, (list, tuple)):
+            for env_var in env_vars_for_provider:
+                key_name = env_var.get("key_name")
+                if key_name and key_name not in UNACCEPTED_ATTRIBUTES:
+                    env_value = os.environ.get(key_name)
+                    if env_value:
+                        # Map environment variable names to recognized parameters
+                        param_key = _normalize_key_name(key_name.lower())
+                        llm_params[param_key] = env_value
+                elif isinstance(env_var, dict):
+                    if env_var.get("default", False):
+                        for key, value in env_var.items():
+                            if key not in ["prompt", "key_name", "default"]:
+                                llm_params[key.lower()] = value
+                else:
+                    print(
+                        f"Expected env_var to be a dictionary, but got {type(env_var)}"
+                    )
 
     # Remove None values
     llm_params = {k: v for k, v in llm_params.items() if v is not None}