"""An agent designed to hold a conversation in addition to using tools."""
from __future__ import annotations
from typing import Any, List, Optional, Sequence, Tuple
from langchain_core._api import deprecated
from langchain_core.agents import AgentAction
from langchain_core.callbacks import BaseCallbackManager
from langchain_core.language_models import BaseLanguageModel
from langchain_core.messages import AIMessage, BaseMessage, HumanMessage
from langchain_core.output_parsers import BaseOutputParser
from langchain_core.prompts import BasePromptTemplate
from langchain_core.prompts.chat import (
ChatPromptTemplate,
HumanMessagePromptTemplate,
MessagesPlaceholder,
SystemMessagePromptTemplate,
)
from langchain_core.tools import BaseTool
from pydantic import Field
from langchain.agents.agent import Agent, AgentOutputParser
from langchain.agents.conversational_chat.output_parser import ConvoOutputParser
from langchain.agents.conversational_chat.prompt import (
PREFIX,
SUFFIX,
TEMPLATE_TOOL_RESPONSE,
)
from langchain.agents.utils import validate_tools_single_input
from langchain.chains import LLMChain
[docs]
@deprecated("0.1.0", alternative="create_json_chat_agent", removal="1.0")
class ConversationalChatAgent(Agent):
"""An agent designed to hold a conversation in addition to using tools."""
output_parser: AgentOutputParser = Field(default_factory=ConvoOutputParser)
"""Output parser for the agent."""
template_tool_response: str = TEMPLATE_TOOL_RESPONSE
"""Template for the tool response."""
@classmethod
def _get_default_output_parser(cls, **kwargs: Any) -> AgentOutputParser:
return ConvoOutputParser()
@property
def _agent_type(self) -> str:
raise NotImplementedError
@property
def observation_prefix(self) -> str:
"""Prefix to append the observation with.
Returns:
"Observation: "
"""
return "Observation: "
@property
def llm_prefix(self) -> str:
"""Prefix to append the llm call with.
Returns:
"Thought: "
"""
return "Thought:"
@classmethod
def _validate_tools(cls, tools: Sequence[BaseTool]) -> None:
super()._validate_tools(tools)
validate_tools_single_input(cls.__name__, tools)
[docs]
@classmethod
def create_prompt(
cls,
tools: Sequence[BaseTool],
system_message: str = PREFIX,
human_message: str = SUFFIX,
input_variables: Optional[List[str]] = None,
output_parser: Optional[BaseOutputParser] = None,
) -> BasePromptTemplate:
"""Create a prompt for the agent.
Args:
tools: The tools to use.
system_message: The system message to use.
Defaults to the PREFIX.
human_message: The human message to use.
Defaults to the SUFFIX.
input_variables: The input variables to use. Defaults to None.
output_parser: The output parser to use. Defaults to None.
Returns:
A PromptTemplate.
"""
tool_strings = "\n".join(
[f"> {tool.name}: {tool.description}" for tool in tools]
)
tool_names = ", ".join([tool.name for tool in tools])
_output_parser = output_parser or cls._get_default_output_parser()
format_instructions = human_message.format(
format_instructions=_output_parser.get_format_instructions()
)
final_prompt = format_instructions.format(
tool_names=tool_names, tools=tool_strings
)
if input_variables is None:
input_variables = ["input", "chat_history", "agent_scratchpad"]
messages = [
SystemMessagePromptTemplate.from_template(system_message),
MessagesPlaceholder(variable_name="chat_history"),
HumanMessagePromptTemplate.from_template(final_prompt),
MessagesPlaceholder(variable_name="agent_scratchpad"),
]
return ChatPromptTemplate(input_variables=input_variables, messages=messages) # type: ignore[arg-type]
def _construct_scratchpad(
self, intermediate_steps: List[Tuple[AgentAction, str]]
) -> List[BaseMessage]:
"""Construct the scratchpad that lets the agent continue its thought process."""
thoughts: List[BaseMessage] = []
for action, observation in intermediate_steps:
thoughts.append(AIMessage(content=action.log))
human_message = HumanMessage(
content=self.template_tool_response.format(observation=observation)
)
thoughts.append(human_message)
return thoughts
