Custom agent

This notebook goes through how to create your own custom agent.

An agent consists of two parts:

- Tools: The tools the agent has available to use.
- The agent class itself: this decides which action to take.
    
    

In this notebook we walk through how to create a custom agent.

from langchain.agents import Tool, AgentExecutor, BaseSingleActionAgent
from langchain import OpenAI, SerpAPIWrapper

API Reference:

• Tool from langchain.agents

search = SerpAPIWrapper()
tools = [
    Tool(
        name="Search",
        func=search.run,
        description="useful for when you need to answer questions about current events",
        return_direct=True,
    )
]

from typing import List, Tuple, Any, Union
from langchain.schema import AgentAction, AgentFinish


class FakeAgent(BaseSingleActionAgent):
    """Fake Custom Agent."""

    @property
    def input_keys(self):
        return ["input"]

    def plan(
        self, intermediate_steps: List[Tuple[AgentAction, str]], **kwargs: Any
    ) -> Union[AgentAction, AgentFinish]:
        """Given input, decided what to do.

        Args:
            intermediate_steps: Steps the LLM has taken to date,
                along with observations
            **kwargs: User inputs.

        Returns:
            Action specifying what tool to use.
        """
        return AgentAction(tool="Search", tool_input=kwargs["input"], log="")

    async def aplan(
        self, intermediate_steps: List[Tuple[AgentAction, str]], **kwargs: Any
    ) -> Union[AgentAction, AgentFinish]:
        """Given input, decided what to do.

        Args:
            intermediate_steps: Steps the LLM has taken to date,
                along with observations
            **kwargs: User inputs.

        Returns:
            Action specifying what tool to use.
        """
        return AgentAction(tool="Search", tool_input=kwargs["input"], log="")

API Reference:

• AgentAction from langchain.schema

agent = FakeAgent()

agent_executor = AgentExecutor.from_agent_and_tools(
    agent=agent, tools=tools, verbose=True
)

agent_executor.run("How many people live in canada as of 2023?")

    
    
    > Entering new AgentExecutor chain...
    The current population of Canada is 38,669,152 as of Monday, April 24, 2023, based on Worldometer elaboration of the latest United Nations data.
    
    > Finished chain.





    'The current population of Canada is 38,669,152 as of Monday, April 24, 2023, based on Worldometer elaboration of the latest United Nations data.'