community[patch]: Fix Playwright Tools bug with Pydantic schemas (#27050)

- Add tests for Playwright tools schema serialization
- Introduce base empty args Input class for BaseBrowserTool

Test Plan: `poetry run pytest
tests/unit_tests/tools/playwright/test_all.py`

Fixes #26758

---------

Co-authored-by: Erick Friis <erick@langchain.dev>
Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>

Author: 3 people

libs/community/extended_testing_deps.txt

@@ -58,6 +58,7 @@ oracledb>=2.2.0,<3
 pandas>=2.0.1,<3
 pdfminer-six>=20221105,<20240706
 pgvector>=0.1.6,<0.2
+playwright>=1.48.0,<2
 praw>=7.7.1,<8
 premai>=0.3.25,<0.4
 psychicapi>=0.8.0,<0.9

libs/community/langchain_community/tools/playwright/current_page.py

@@ -15,12 +15,16 @@
 )
 
 
+class CurrentWebPageToolInput(BaseModel):
+    """Explicit no-args input for CurrentWebPageTool."""
+
+
 class CurrentWebPageTool(BaseBrowserTool):  # type: ignore[override, override]
     """Tool for getting the URL of the current webpage."""
 
     name: str = "current_webpage"
     description: str = "Returns the URL of the current page"
-    args_schema: Type[BaseModel] = BaseModel
+    args_schema: Type[BaseModel] = CurrentWebPageToolInput
 
     def _run(
         self,

libs/community/langchain_community/tools/playwright/extract_text.py

@@ -15,12 +15,16 @@
 )
 
 
+class ExtractTextToolInput(BaseModel):
+    """Explicit no-args input for ExtractTextTool."""
+
+
 class ExtractTextTool(BaseBrowserTool):  # type: ignore[override, override]
     """Tool for extracting all the text on the current webpage."""
 
     name: str = "extract_text"
     description: str = "Extract all the text on the current webpage"
-    args_schema: Type[BaseModel] = BaseModel
+    args_schema: Type[BaseModel] = ExtractTextToolInput
 
     @model_validator(mode="before")
     @classmethod

libs/community/langchain_community/tools/playwright/navigate_back.py

@@ -15,12 +15,16 @@
 )
 
 
+class NavigateBackToolInput(BaseModel):
+    """Explicit no-args input for NavigateBackTool."""
+
+
 class NavigateBackTool(BaseBrowserTool):  # type: ignore[override, override]
     """Navigate back to the previous page in the browser history."""
 
     name: str = "previous_webpage"
     description: str = "Navigate back to the previous page in the browser history"
-    args_schema: Type[BaseModel] = BaseModel
+    args_schema: Type[BaseModel] = NavigateBackToolInput
 
     def _run(self, run_manager: Optional[CallbackManagerForToolRun] = None) -> str:
         """Use the tool."""

libs/community/tests/unit_tests/tools/playwright/__init__.py

@@ -0,0 +1,26 @@
+"""Test Playwright's Tools."""
+
+from unittest.mock import Mock
+
+import pytest
+
+from langchain_community.agent_toolkits import PlayWrightBrowserToolkit
+
+
+@pytest.mark.requires("playwright")
+@pytest.mark.requires("bs4")
+def test_playwright_tools_schemas() -> None:
+    """Test calling 'tool_call_schema' for every tool to check to init issues."""
+
+    from playwright.sync_api import Browser
+
+    sync_browser = Mock(spec=Browser)
+    tools = PlayWrightBrowserToolkit.from_browser(sync_browser=sync_browser).get_tools()
+
+    for tool in tools:
+        try:
+            tool.tool_call_schema
+        except Exception as e:
+            raise AssertionError(
+                f"Error for '{tool.name}' tool: {type(e).__name__}: {e}"
+            ) from e