description = "useful for when you need to answer questions about current events"
    def _run(self, query: str, engine: str = "google", gl: str = "us", hl: str = "en", run_manager: Optional[CallbackManagerForToolRun] = None) -> str:
        """Use the tool."""
        search_wrapper = SerpAPIWrapper(params={"engine": engine, "gl": gl, "hl": hl})
        return search_wrapper.run(query)
    
    async def _arun(self, query: str,  engine: str = "google", gl: str = "us", hl: str = "en", run_manager: Optional[AsyncCallbackManagerForToolRun] = None) -> str:
        """Use the tool asynchronously."""
        raise NotImplementedError("custom_search does not support async")
# You can provide a custom args schema to add descriptions or custom validation
class SearchSchema(BaseModel):
    query: str = Field(description="should be a search query")
    engine: str = Field(description="should be a search engine")
    gl: str = Field(description="should be a country code")
    hl: str = Field(description="should be a language code")
class CustomSearchTool(BaseTool):
    name = "custom_search"
    description = "useful for when you need to answer questions about current events"
    args_schema: Type[SearchSchema] = SearchSchema
    def _run(self, query: str, engine: str = "google", gl: str = "us", hl: str = "en", run_manager: Optional[CallbackManagerForToolRun] = None) -> str:
        """Use the tool."""
        search_wrapper = SerpAPIWrapper(params={"engine": engine, "gl": gl, "hl": hl})
        return search_wrapper.run(query)
rtdocs_stable/api.python.langchain.com/en/stable/modules/agents/tools/custom_tools.html