update notebook and make backwards compatible (#772)

Author: hwchase17

docs/modules/agents/examples/custom_agent.ipynb

@@ -53,7 +53,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 2,
    "id": "becda2a1",
    "metadata": {},
    "outputs": [],
@@ -70,7 +70,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": 3,
    "id": "339b1bb8",
    "metadata": {},
    "outputs": [],
@@ -99,7 +99,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 7,
+   "execution_count": 4,
    "id": "e21d2098",
    "metadata": {},
    "outputs": [
@@ -134,7 +134,6 @@
    ]
   },
   {
-   "attachments": {},
    "cell_type": "markdown",
    "id": "5e028e6d",
    "metadata": {},
@@ -146,7 +145,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 16,
+   "execution_count": 5,
    "id": "9b1cc2a2",
    "metadata": {},
    "outputs": [],
@@ -156,17 +155,18 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 17,
+   "execution_count": 7,
    "id": "e4f5092f",
    "metadata": {},
    "outputs": [],
    "source": [
-    "agent = ZeroShotAgent(llm_chain=llm_chain, tools=tools)"
+    "tool_names = [tool.name for tool in tools]\n",
+    "agent = ZeroShotAgent(llm_chain=llm_chain, allowed_tools=tool_names)"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 18,
+   "execution_count": 8,
    "id": "490604e9",
    "metadata": {},
    "outputs": [],
@@ -176,7 +176,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
+   "execution_count": 9,
    "id": "653b1617",
    "metadata": {},
    "outputs": [
@@ -191,22 +191,23 @@
       "Action: Search\n",
       "Action Input: Population of Canada\u001b[0m\n",
       "Observation: \u001b[36;1m\u001b[1;3mCanada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over 9.98 million square kilometres, making it the world's second-largest country by total area.\u001b[0m\n",
-      "Thought:\u001b[32;1m\u001b[1;3m I need to find out the exact population of Canada\n",
+      "Thought:\u001b[32;1m\u001b[1;3m I need to find out the population of Canada\n",
       "Action: Search\n",
-      "Action Input: Population of Canada 2020\u001b[0m\n",
+      "Action Input: Population of Canada\u001b[0m\n",
       "Observation: \u001b[36;1m\u001b[1;3mCanada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over 9.98 million square kilometres, making it the world's second-largest country by total area.\u001b[0m\n",
       "Thought:\u001b[32;1m\u001b[1;3m I now know the population of Canada\n",
-      "Final Answer: Arrr, Canada be home to 37.59 million people!\u001b[0m\n",
-      "\u001b[1m> Finished AgentExecutor chain.\u001b[0m\n"
+      "Final Answer: Arrr, Canada be home to over 37 million people!\u001b[0m\n",
+      "\n",
+      "\u001b[1m> Finished chain.\u001b[0m\n"
      ]
     },
     {
      "data": {
       "text/plain": [
-       "'Arrr, Canada be home to 37.59 million people!'"
+       "'Arrr, Canada be home to over 37 million people!'"
       ]
      },
-     "execution_count": 19,
+     "execution_count": 9,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -361,7 +362,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python 3 (ipykernel)",
    "language": "python",
    "name": "python3"
   },
@@ -375,7 +376,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.8.12 (default, Feb 15 2022, 17:41:09) \n[Clang 12.0.5 (clang-1205.0.22.11)]"
+   "version": "3.10.9"
   },
   "vscode": {
    "interpreter": {

langchain/agents/agent.py

@@ -33,7 +33,7 @@ class Agent(BaseModel):
     """
 
     llm_chain: LLMChain
-    allowed_tools: List[str]
+    allowed_tools: Optional[List[str]] = None
     return_values: List[str] = ["output"]
 
     @abstractmethod
@@ -269,11 +269,12 @@ def validate_tools(cls, values: Dict) -> Dict:
         """Validate that tools are compatible with agent."""
         agent = values["agent"]
         tools = values["tools"]
-        if set(agent.allowed_tools) != set([tool.name for tool in tools]):
-            raise ValueError(
-                f"Allowed tools ({agent.allowed_tools}) different than "
-                f"provided tools ({[tool.name for tool in tools]})"
-            )
+        if agent.allowed_tools is not None:
+            if set(agent.allowed_tools) != set([tool.name for tool in tools]):
+                raise ValueError(
+                    f"Allowed tools ({agent.allowed_tools}) different than "
+                    f"provided tools ({[tool.name for tool in tools]})"
+                )
         return values
 
     def save(self, file_path: Union[Path, str]) -> None: