diff --git a/.env.template b/.env.template
index 2487ab90..c1bfacc6 100644
--- a/.env.template
+++ b/.env.template
@@ -66,11 +66,11 @@ OPENAI_API_KEY=your-openai-api-key
 ### LLM MODELS
 ################################################################################
 
-## SMART_LLM - Smart language model (Default: gpt-4)
-# SMART_LLM=gpt-4
+## SMART_LLM - Smart language model (Default: gpt-4-0314)
+# SMART_LLM=gpt-4-0314
 
-## FAST_LLM - Fast language model (Default: gpt-3.5-turbo)
-# FAST_LLM=gpt-3.5-turbo
+## FAST_LLM - Fast language model (Default: gpt-3.5-turbo-16k)
+# FAST_LLM=gpt-3.5-turbo-16k
 
 ## EMBEDDING_MODEL - Model to use for creating embeddings
 # EMBEDDING_MODEL=text-embedding-ada-002
diff --git a/autogpt/agents/agent.py b/autogpt/agents/agent.py
index 9c1a7d73..8460292a 100644
--- a/autogpt/agents/agent.py
+++ b/autogpt/agents/agent.py
@@ -35,6 +35,7 @@ from autogpt.models.context_item import ContextItem
 
 from .base import BaseAgent
 from .features.context import ContextMixin
+from .features.watchdog import WatchdogMixin
 from .features.workspace import WorkspaceMixin
 from .utils.exceptions import (
     AgentException,
@@ -46,7 +47,7 @@ from .utils.exceptions import (
 logger = logging.getLogger(__name__)
 
 
-class Agent(ContextMixin, WorkspaceMixin, BaseAgent):
+class Agent(ContextMixin, WorkspaceMixin, WatchdogMixin, BaseAgent):
     """Agent class for interacting with Auto-GPT."""
 
     def __init__(
diff --git a/autogpt/agents/base.py b/autogpt/agents/base.py
index 28f69602..e530557e 100644
--- a/autogpt/agents/base.py
+++ b/autogpt/agents/base.py
@@ -7,11 +7,12 @@ from typing import TYPE_CHECKING, Any, Literal, Optional
 
 if TYPE_CHECKING:
     from autogpt.config import AIConfig, Config
+    from autogpt.llm.base import ChatModelInfo, ChatModelResponse
     from autogpt.models.command_registry import CommandRegistry
 
 from autogpt.agents.utils.exceptions import InvalidAgentResponseError
 from autogpt.config.ai_directives import AIDirectives
-from autogpt.llm.base import ChatModelResponse, ChatSequence, Message
+from autogpt.llm.base import ChatSequence, Message
 from autogpt.llm.providers.openai import OPEN_AI_CHAT_MODELS, get_openai_command_specs
 from autogpt.llm.utils import count_message_tokens, create_chat_completion
 from autogpt.memory.message_history import MessageHistory
@@ -83,10 +84,6 @@ class BaseAgent(metaclass=ABCMeta):
         self.cycle_count = 0
         """The number of cycles that the agent has run since its initialization."""
 
-        llm_name = self.config.smart_llm if self.big_brain else self.config.fast_llm
-        self.llm = OPEN_AI_CHAT_MODELS[llm_name]
-        """The LLM that the agent uses to think."""
-
         self.send_token_limit = send_token_limit or self.llm.max_tokens * 3 // 4
         """
         The token limit for prompt construction. Should leave room for the completion;
@@ -111,6 +108,12 @@ class BaseAgent(metaclass=ABCMeta):
         """
         return self.prompt_generator.construct_system_prompt(self)
 
+    @property
+    def llm(self) -> ChatModelInfo:
+        """The LLM that the agent uses to think."""
+        llm_name = self.config.smart_llm if self.big_brain else self.config.fast_llm
+        return OPEN_AI_CHAT_MODELS[llm_name]
+
     def think(
         self,
         instruction: Optional[str] = None,
diff --git a/autogpt/agents/features/watchdog.py b/autogpt/agents/features/watchdog.py
new file mode 100644
index 00000000..850999fd
--- /dev/null
+++ b/autogpt/agents/features/watchdog.py
@@ -0,0 +1,59 @@
+from __future__ import annotations
+
+import logging
+from contextlib import ExitStack
+
+from autogpt.models.agent_actions import ActionHistory
+
+from ..base import BaseAgent
+
+logger = logging.getLogger(__name__)
+
+
+class WatchdogMixin:
+    """
+    Mixin that adds a watchdog feature to an agent class. Whenever the agent starts
+    looping, the watchdog will switch from the FAST_LLM to the SMART_LLM and re-think.
+    """
+
+    event_history: ActionHistory
+
+    def __init__(self, **kwargs) -> None:
+        # Initialize other bases first, because we need the event_history from BaseAgent
+        super(WatchdogMixin, self).__init__(**kwargs)
+
+        if not isinstance(self, BaseAgent):
+            raise NotImplementedError(
+                f"{__class__.__name__} can only be applied to BaseAgent derivatives"
+            )
+
+    def think(self, *args, **kwargs) -> BaseAgent.ThoughtProcessOutput:
+        command_name, command_args, thoughts = super(WatchdogMixin, self).think(
+            *args, **kwargs
+        )
+
+        if not self.big_brain and len(self.event_history) > 1:
+            # Detect repetitive commands
+            previous_cycle = self.event_history.cycles[self.event_history.cursor - 1]
+            if (
+                command_name == previous_cycle.action.name
+                and command_args == previous_cycle.action.args
+            ):
+                logger.info(
+                    f"Repetitive command detected ({command_name}), re-thinking with SMART_LLM..."
+                )
+                with ExitStack() as stack:
+
+                    @stack.callback
+                    def restore_state() -> None:
+                        # Executed after exiting the ExitStack context
+                        self.big_brain = False
+
+                    # Remove partial record of current cycle
+                    self.event_history.rewind()
+
+                    # Switch to SMART_LLM and re-think
+                    self.big_brain = True
+                    return self.think(*args, **kwargs)
+
+        return command_name, command_args, thoughts
diff --git a/autogpt/config/config.py b/autogpt/config/config.py
index f47c22c3..3dc2fc00 100644
--- a/autogpt/config/config.py
+++ b/autogpt/config/config.py
@@ -55,7 +55,7 @@ class Config(SystemSettings, arbitrary_types_allowed=True):
     workspace_path: Optional[Path] = None
     file_logger_path: Optional[Path] = None
     # Model configuration
-    fast_llm: str = "gpt-3.5-turbo"
+    fast_llm: str = "gpt-3.5-turbo-16k"
     smart_llm: str = "gpt-4-0314"
     temperature: float = 0
     openai_functions: bool = False
diff --git a/autogpt/models/agent_actions.py b/autogpt/models/agent_actions.py
index 676c403e..bf88e424 100644
--- a/autogpt/models/agent_actions.py
+++ b/autogpt/models/agent_actions.py
@@ -103,6 +103,23 @@ class ActionHistory:
         self.current_record.result = result
         self.cursor = len(self.cycles)
 
+    def rewind(self, number_of_cycles: int = 0) -> None:
+        """Resets the history to an earlier state.
+
+        Params:
+            number_of_cycles (int): The number of cycles to rewind. Default is 0.
+                When set to 0, it will only reset the current cycle.
+        """
+        # Remove partial record of current cycle
+        if self.current_record:
+            if self.current_record.action and not self.current_record.result:
+                self.cycles.pop(self.cursor)
+
+        # Rewind the specified number of cycles
+        if number_of_cycles > 0:
+            self.cycles = self.cycles[:-number_of_cycles]
+            self.cursor = len(self.cycles)
+
     def fmt_list(self) -> str:
         return format_numbered_list(self.cycles)
 
diff --git a/autogpt/models/command.py b/autogpt/models/command.py
index 48f913cf..0e1e8d87 100644
--- a/autogpt/models/command.py
+++ b/autogpt/models/command.py
@@ -45,11 +45,13 @@ class Command:
     def __call__(self, *args, agent: BaseAgent, **kwargs) -> Any:
         if callable(self.enabled) and not self.enabled(agent.config):
             if self.disabled_reason:
-                return f"Command '{self.name}' is disabled: {self.disabled_reason}"
-            return f"Command '{self.name}' is disabled"
+                raise RuntimeError(
+                    f"Command '{self.name}' is disabled: {self.disabled_reason}"
+                )
+            raise RuntimeError(f"Command '{self.name}' is disabled")
 
         if callable(self.available) and not self.available(agent):
-            return f"Command '{self.name}' is not available"
+            raise RuntimeError(f"Command '{self.name}' is not available")
 
         return self.method(*args, **kwargs, agent=agent)