From 32f8f39974961b097fceab158f573174e0553450 Mon Sep 17 00:00:00 2001
From: Bagatur <22008038+baskaryan@users.noreply.github.com>
Date: Tue, 25 Jun 2024 15:26:35 -0700
Subject: [PATCH] core[patch]: use args_schema doc for tool description
 (#23503)

---
 libs/core/langchain_core/tools.py        | 2 ++
 libs/core/tests/unit_tests/test_tools.py | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/libs/core/langchain_core/tools.py b/libs/core/langchain_core/tools.py
index 86cedd51aa9..cf168e784b2 100644
--- a/libs/core/langchain_core/tools.py
+++ b/libs/core/langchain_core/tools.py
@@ -827,6 +827,8 @@ class StructuredTool(BaseTool):
             raise ValueError("Function and/or coroutine must be provided")
         name = name or source_function.__name__
         description_ = description or source_function.__doc__
+        if description_ is None and args_schema:
+            description_ = args_schema.__doc__
         if description_ is None:
             raise ValueError(
                 "Function must have a docstring if description not provided."
diff --git a/libs/core/tests/unit_tests/test_tools.py b/libs/core/tests/unit_tests/test_tools.py
index cc624f4cfd2..5e7b05dbff3 100644
--- a/libs/core/tests/unit_tests/test_tools.py
+++ b/libs/core/tests/unit_tests/test_tools.py
@@ -44,6 +44,8 @@ def test_unnamed_decorator() -> None:
 
 
 class _MockSchema(BaseModel):
+    """Return the arguments directly."""
+
     arg1: int
     arg2: bool
     arg3: Optional[dict] = None
@@ -133,7 +135,6 @@ def test_decorator_with_specified_schema() -> None:
 
     @tool(args_schema=_MockSchema)
     def tool_func(arg1: int, arg2: bool, arg3: Optional[dict] = None) -> str:
-        """Return the arguments directly."""
         return f"{arg1} {arg2} {arg3}"
 
     assert isinstance(tool_func, BaseTool)