Harrison/tool decorator (#790)

Co-authored-by: Jason Liu <jxnl@users.noreply.github.com>
Co-authored-by: Jason Liu <jason@jxnl.coA>

docs/modules/agents/examples/custom_tools.ipynb

@@ -10,15 +10,17 @@
     "When constructing your own agent, you will need to provide it with a list of Tools that it can use. A Tool is defined as below.\n",
     "\n",
     "```python\n",
-    "class Tool(NamedTuple):\n",
+    "@dataclass \n",
+    "class Tool:\n",
     "    \"\"\"Interface for tools.\"\"\"\n",
     "\n",
     "    name: str\n",
     "    func: Callable[[str], str]\n",
     "    description: Optional[str] = None\n",
+    "    return_direct: bool = True\n",
     "```\n",
     "\n",
-    "The two required components of a Tool are the name and then the tool itself. A tool description is optional, as it is needed for some agents but not all."
+    "The two required components of a Tool are the name and then the tool itself. A tool description is optional, as it is needed for some agents but not all. You can create these tools directly, but we also provide a decorator to easily convert any function into a tool."
    ]
   },
   {
@@ -151,6 +153,94 @@
     "agent.run(\"Who is Olivia Wilde's boyfriend? What is his current age raised to the 0.23 power?\")"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "824eaf74",
+   "metadata": {},
+   "source": [
+    "## Using the `tool` decorator\n",
+    "\n",
+    "To make it easier to define custom tools, a `@tool` decorator is provided. This decorator can be used to quickly create a `Tool` from a simple function. The decorator uses the function name as the tool name by default, but this can be overridden by passing a string as the first argument. Additionally, the decorator will use the function's docstring as the tool's description."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "id": "8f15307d",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain.agents import tool\n",
+    "\n",
+    "@tool\n",
+    "def search_api(query: str) -> str:\n",
+    "    \"\"\"Searches the API for the query.\"\"\"\n",
+    "    return \"Results\""
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "id": "0a23b91b",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Tool(name='search_api', func=<function search_api at 0x10dad7d90>, description='search_api(query: str) -> str - Searches the API for the query.', return_direct=False)"
+      ]
+     },
+     "execution_count": 2,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "search_api"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "cc6ee8c1",
+   "metadata": {},
+   "source": [
+    "You can also provide arguments like the tool name and whether to return directly."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "id": "28cdf04d",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "@tool(\"search\", return_direct=True)\n",
+    "def search_api(query: str) -> str:\n",
+    "    \"\"\"Searches the API for the query.\"\"\"\n",
+    "    return \"Results\""
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "id": "1085a4bd",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "Tool(name='search', func=<function search_api at 0x112301bd0>, description='search(query: str) -> str - Searches the API for the query.', return_direct=True)"
+      ]
+     },
+     "execution_count": 4,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "search_api"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "1d0430d6",
@@ -432,7 +522,7 @@
   },
   "vscode": {
    "interpreter": {
-    "hash": "cb23c3a7a387ab03496baa08507270f8e0861b23170e79d5edc545893cdca840"
+    "hash": "e90c8aa204a57276aa905271aff2d11799d0acb3547adabc5892e639a5e45e34"
    }
   }
  },