diff --git a/docs/docs/how_to/custom_tools.ipynb b/docs/docs/how_to/custom_tools.ipynb
index 49d54908ff2..487af8d5260 100644
--- a/docs/docs/how_to/custom_tools.ipynb
+++ b/docs/docs/how_to/custom_tools.ipynb
@@ -511,7 +511,7 @@
     "    CallbackManagerForToolRun,\n",
     ")\n",
     "from langchain_core.tools import BaseTool\n",
-    "from pydantic import BaseModel\n",
+    "from pydantic import BaseModel, Field\n",
     "\n",
     "\n",
     "class CalculatorInput(BaseModel):\n",