diff --git a/langchain/agents/agent.py b/langchain/agents/agent.py
index eb9b859f..ca382031 100644
--- a/langchain/agents/agent.py
+++ b/langchain/agents/agent.py
@@ -7,7 +7,7 @@ import logging
 import time
 from abc import abstractmethod
 from pathlib import Path
-from typing import Any, Dict, List, Optional, Sequence, Tuple, Union
+from typing import Any, Dict, List, Optional, Sequence, Set, Tuple, Union
 
 import yaml
 from pydantic import BaseModel, root_validator
@@ -46,8 +46,8 @@ class BaseSingleActionAgent(BaseModel):
         """Return values of the agent."""
         return ["output"]
 
-    def get_allowed_tools(self) -> Optional[List[str]]:
-        return None
+    def get_allowed_tools(self) -> Set[str]:
+        return set()
 
     @abstractmethod
     def plan(
@@ -178,8 +178,8 @@ class BaseMultiActionAgent(BaseModel):
         """Return values of the agent."""
         return ["output"]
 
-    def get_allowed_tools(self) -> Optional[List[str]]:
-        return None
+    def get_allowed_tools(self) -> Set[str]:
+        return set()
 
     @abstractmethod
     def plan(
@@ -372,9 +372,9 @@ class Agent(BaseSingleActionAgent):
 
     llm_chain: LLMChain
     output_parser: AgentOutputParser
-    allowed_tools: Optional[List[str]] = None
+    allowed_tools: Set[str] = set()
 
-    def get_allowed_tools(self) -> Optional[List[str]]:
+    def get_allowed_tools(self) -> Set[str]:
         return self.allowed_tools
 
     @property
@@ -607,12 +607,11 @@ class AgentExecutor(Chain):
         agent = values["agent"]
         tools = values["tools"]
         allowed_tools = agent.get_allowed_tools()
-        if allowed_tools is not None:
-            if set(allowed_tools) != set([tool.name for tool in tools]):
-                raise ValueError(
-                    f"Allowed tools ({allowed_tools}) different than "
-                    f"provided tools ({[tool.name for tool in tools]})"
-                )
+        if allowed_tools != set([tool.name for tool in tools]):
+            raise ValueError(
+                f"Allowed tools ({allowed_tools}) different than "
+                f"provided tools ({[tool.name for tool in tools]})"
+            )
         return values
 
     @root_validator()
diff --git a/tests/integration_tests/agent/__init__.py b/tests/integration_tests/agent/__init__.py
new file mode 100644
index 00000000..117480e1
--- /dev/null
+++ b/tests/integration_tests/agent/__init__.py
@@ -0,0 +1 @@
+"""All integration tests for agent."""
diff --git a/tests/integration_tests/agent/test_agent.py b/tests/integration_tests/agent/test_agent.py
new file mode 100644
index 00000000..b423414e
--- /dev/null
+++ b/tests/integration_tests/agent/test_agent.py
@@ -0,0 +1,16 @@
+from langchain.agents.chat.base import ChatAgent
+from langchain.llms.openai import OpenAI
+from langchain.tools.ddg_search.tool import DuckDuckGoSearchRun
+
+
+class TestAgent:
+    def test_agent_generation(self) -> None:
+        web_search = DuckDuckGoSearchRun()
+        tools = [web_search]
+        agent = ChatAgent.from_llm_and_tools(
+            ai_name="Tom",
+            ai_role="Assistant",
+            tools=tools,
+            llm=OpenAI(maxTokens=10),
+        )
+        assert agent.allowed_tools == set([web_search.name])