update OpenAI function agents' llm validation (#13538)

- **Description:** This PR modifies the LLM validation in OpenAI
function agents to check whether the LLM supports OpenAI functions based
on a property (`supports_oia_functions`) instead of whether the LLM
passed to the agent `isinstance` of `ChatOpenAI`. This allows classes
that extend `BaseChatModel` to be passed to these agents as long as
they've been integrated with the OpenAI APIs and have this property set,
even if they don't extend `ChatOpenAI`.
  - **Issue:** N/A
  - **Dependencies:** none

libs/langchain/langchain/agents/agent_toolkits/conversational_retrieval/openai_functions.py

@@ -10,7 +10,6 @@ from langchain.agents.openai_functions_agent.agent_token_buffer_memory import (
     AgentTokenBufferMemory,
 )
 from langchain.agents.openai_functions_agent.base import OpenAIFunctionsAgent
-from langchain.chat_models.openai import ChatOpenAI
 from langchain.memory.token_buffer import ConversationTokenBufferMemory
 from langchain.tools.base import BaseTool
 
@@ -57,8 +56,6 @@ def create_conversational_retrieval_agent(
         An agent executor initialized appropriately
     """
 
-    if not isinstance(llm, ChatOpenAI):
-        raise ValueError("Only supported with ChatOpenAI models.")
     if remember_intermediate_steps:
         memory: BaseMemory = AgentTokenBufferMemory(
             memory_key=memory_key, llm=llm, max_token_limit=max_token_limit

libs/langchain/langchain/agents/openai_functions_agent/base.py

@@ -25,7 +25,6 @@ from langchain.agents.output_parsers.openai_functions import (
 )
 from langchain.callbacks.base import BaseCallbackManager
 from langchain.callbacks.manager import Callbacks
-from langchain.chat_models.openai import ChatOpenAI
 from langchain.tools.base import BaseTool
 from langchain.tools.render import format_tool_to_openai_function
 
@@ -50,12 +49,6 @@ class OpenAIFunctionsAgent(BaseSingleActionAgent):
         """Get allowed tools."""
         return [t.name for t in self.tools]
 
-    @root_validator
-    def validate_llm(cls, values: dict) -> dict:
-        if not isinstance(values["llm"], ChatOpenAI):
-            raise ValueError("Only supported with ChatOpenAI models.")
-        return values
-
     @root_validator
     def validate_prompt(cls, values: dict) -> dict:
         prompt: BasePromptTemplate = values["prompt"]
@@ -222,8 +215,6 @@ class OpenAIFunctionsAgent(BaseSingleActionAgent):
         **kwargs: Any,
     ) -> BaseSingleActionAgent:
         """Construct an agent from an LLM and tools."""
-        if not isinstance(llm, ChatOpenAI):
-            raise ValueError("Only supported with ChatOpenAI models.")
         prompt = cls.create_prompt(
             extra_prompt_messages=extra_prompt_messages,
             system_message=system_message,

libs/langchain/langchain/agents/openai_functions_multi_agent/base.py

@@ -26,7 +26,6 @@ from langchain.agents.format_scratchpad.openai_functions import (
 )
 from langchain.callbacks.base import BaseCallbackManager
 from langchain.callbacks.manager import Callbacks
-from langchain.chat_models.openai import ChatOpenAI
 from langchain.tools import BaseTool
 
 # For backwards compatibility
@@ -109,12 +108,6 @@ class OpenAIMultiFunctionsAgent(BaseMultiActionAgent):
         """Get allowed tools."""
         return [t.name for t in self.tools]
 
-    @root_validator
-    def validate_llm(cls, values: dict) -> dict:
-        if not isinstance(values["llm"], ChatOpenAI):
-            raise ValueError("Only supported with ChatOpenAI models.")
-        return values
-
     @root_validator
     def validate_prompt(cls, values: dict) -> dict:
         prompt: BasePromptTemplate = values["prompt"]