langchain[patch]: update deprecation message for agent classes and co…

…nstructors (#28369)

libs/langchain/langchain/_api/deprecation.py

@@ -7,7 +7,20 @@
     warn_deprecated,
 )
 
+AGENT_DEPRECATION_WARNING = (
+    "LangChain agents will continue to be supported, but it is recommended for new "
+    "use cases to be built with LangGraph. LangGraph offers a more flexible and "
+    "full-featured framework for building agents, including support for "
+    "tool-calling, persistence of state, and human-in-the-loop workflows. See "
+    "LangGraph documentation for more details: "
+    "https://langchain-ai.github.io/langgraph/. Refer here for its pre-built "
+    "ReAct agent: "
+    "https://langchain-ai.github.io/langgraph/how-tos/create-react-agent/"
+)
+
+
 __all__ = [
+    "AGENT_DEPRECATION_WARNING",
     "LangChainDeprecationWarning",
     "LangChainPendingDeprecationWarning",
     "deprecated",

libs/langchain/langchain/agents/agent.py

@@ -47,6 +47,7 @@
 from pydantic import BaseModel, ConfigDict, model_validator
 from typing_extensions import Self
 
+from langchain._api.deprecation import AGENT_DEPRECATION_WARNING
 from langchain.agents.agent_iterator import AgentExecutorIterator
 from langchain.agents.agent_types import AgentType
 from langchain.agents.tools import InvalidTool
@@ -633,10 +634,7 @@ async def aplan(
 
 @deprecated(
     "0.1.0",
-    message=(
-        "Use new agent constructor methods like create_react_agent, create_json_agent, "
-        "create_structured_chat_agent, etc."
-    ),
+    message=AGENT_DEPRECATION_WARNING,
     removal="1.0",
 )
 class LLMSingleActionAgent(BaseSingleActionAgent):
@@ -724,10 +722,7 @@ def tool_run_logging_kwargs(self) -> Dict:
 
 @deprecated(
     "0.1.0",
-    message=(
-        "Use new agent constructor methods like create_react_agent, create_json_agent, "
-        "create_structured_chat_agent, etc."
-    ),
+    message=AGENT_DEPRECATION_WARNING,
     removal="1.0",
 )
 class Agent(BaseSingleActionAgent):

libs/langchain/langchain/agents/agent_toolkits/vectorstore/base.py

@@ -20,6 +20,10 @@
     since="0.2.13",
     removal="1.0",
     message=(
+        "This function will continue to be supported, but it is recommended for new "
+        "use cases to be built with LangGraph. LangGraph offers a more flexible and "
+        "full-featured framework for building agents, including support for "
+        "tool-calling, persistence of state, and human-in-the-loop workflows. "
         "See API reference for this function for a replacement implementation: "
         "https://api.python.langchain.com/en/latest/agents/langchain.agents.agent_toolkits.vectorstore.base.create_vectorstore_agent.html "  # noqa: E501
         "Read more here on how to create agents that query vector stores: "
@@ -109,6 +113,10 @@ def create_vectorstore_agent(
     since="0.2.13",
     removal="1.0",
     message=(
+        "This function will continue to be supported, but it is recommended for new "
+        "use cases to be built with LangGraph. LangGraph offers a more flexible and "
+        "full-featured framework for building agents, including support for "
+        "tool-calling, persistence of state, and human-in-the-loop workflows. "
         "See API reference for this function for a replacement implementation: "
         "https://api.python.langchain.com/en/latest/agents/langchain.agents.agent_toolkits.vectorstore.base.create_vectorstore_router_agent.html "  # noqa: E501
         "Read more here on how to create agents that query vector stores: "

libs/langchain/langchain/agents/agent_types.py

@@ -4,13 +4,12 @@
 
 from langchain_core._api import deprecated
 
+from langchain._api.deprecation import AGENT_DEPRECATION_WARNING
+
 
 @deprecated(
     "0.1.0",
-    message=(
-        "Use new agent constructor methods like create_react_agent, create_json_agent, "
-        "create_structured_chat_agent, etc."
-    ),
+    message=AGENT_DEPRECATION_WARNING,
     removal="1.0",
 )
 class AgentType(str, Enum):

libs/langchain/langchain/agents/chat/base.py

@@ -13,6 +13,7 @@
 from langchain_core.tools import BaseTool
 from pydantic import Field
 
+from langchain._api.deprecation import AGENT_DEPRECATION_WARNING
 from langchain.agents.agent import Agent, AgentOutputParser
 from langchain.agents.chat.output_parser import ChatOutputParser
 from langchain.agents.chat.prompt import (
@@ -25,7 +26,11 @@
 from langchain.chains.llm import LLMChain
 
 
-@deprecated("0.1.0", alternative="create_react_agent", removal="1.0")
+@deprecated(
+    "0.1.0",
+    message=AGENT_DEPRECATION_WARNING,
+    removal="1.0",
+)
 class ChatAgent(Agent):
     """Chat Agent."""
 

libs/langchain/langchain/agents/conversational/base.py

@@ -11,6 +11,7 @@
 from langchain_core.tools import BaseTool
 from pydantic import Field
 
+from langchain._api.deprecation import AGENT_DEPRECATION_WARNING
 from langchain.agents.agent import Agent, AgentOutputParser
 from langchain.agents.agent_types import AgentType
 from langchain.agents.conversational.output_parser import ConvoOutputParser
@@ -19,7 +20,11 @@
 from langchain.chains import LLMChain
 
 
-@deprecated("0.1.0", alternative="create_react_agent", removal="1.0")
+@deprecated(
+    "0.1.0",
+    message=AGENT_DEPRECATION_WARNING,
+    removal="1.0",
+)
 class ConversationalAgent(Agent):
     """An agent that holds a conversation in addition to using tools."""
 

libs/langchain/langchain/agents/initialize.py

@@ -7,17 +7,15 @@
 from langchain_core.language_models import BaseLanguageModel
 from langchain_core.tools import BaseTool
 
+from langchain._api.deprecation import AGENT_DEPRECATION_WARNING
 from langchain.agents.agent import AgentExecutor
 from langchain.agents.agent_types import AgentType
 from langchain.agents.loading import AGENT_TO_CLASS, load_agent
 
 
 @deprecated(
     "0.1.0",
-    alternative=(
-        "Use new agent constructor methods like create_react_agent, create_json_agent, "
-        "create_structured_chat_agent, etc."
-    ),
+    message=AGENT_DEPRECATION_WARNING,
     removal="1.0",
 )
 def initialize_agent(

libs/langchain/langchain/agents/mrkl/base.py

@@ -12,6 +12,7 @@
 from langchain_core.tools.render import render_text_description
 from pydantic import Field
 
+from langchain._api.deprecation import AGENT_DEPRECATION_WARNING
 from langchain.agents.agent import Agent, AgentExecutor, AgentOutputParser
 from langchain.agents.agent_types import AgentType
 from langchain.agents.mrkl.output_parser import MRKLOutputParser
@@ -34,7 +35,11 @@ class ChainConfig(NamedTuple):
     action_description: str
 
 
-@deprecated("0.1.0", alternative="create_react_agent", removal="1.0")
+@deprecated(
+    "0.1.0",
+    message=AGENT_DEPRECATION_WARNING,
+    removal="1.0",
+)
 class ZeroShotAgent(Agent):
     """Agent for the MRKL chain.
 
@@ -168,7 +173,11 @@ def _validate_tools(cls, tools: Sequence[BaseTool]) -> None:
         super()._validate_tools(tools)
 
 
-@deprecated("0.1.0", removal="1.0")
+@deprecated(
+    "0.1.0",
+    message=AGENT_DEPRECATION_WARNING,
+    removal="1.0",
+)
 class MRKLChain(AgentExecutor):
     """Chain that implements the MRKL system."""
 

libs/langchain/langchain/agents/react/base.py

@@ -11,6 +11,7 @@
 from langchain_core.tools import BaseTool, Tool
 from pydantic import Field
 
+from langchain._api.deprecation import AGENT_DEPRECATION_WARNING
 from langchain.agents.agent import Agent, AgentExecutor, AgentOutputParser
 from langchain.agents.agent_types import AgentType
 from langchain.agents.react.output_parser import ReActOutputParser
@@ -22,7 +23,11 @@
     from langchain_community.docstore.base import Docstore
 
 
-@deprecated("0.1.0", removal="1.0")
+@deprecated(
+    "0.1.0",
+    message=AGENT_DEPRECATION_WARNING,
+    removal="1.0",
+)
 class ReActDocstoreAgent(Agent):
     """Agent for the ReAct chain."""
 
@@ -69,7 +74,11 @@ def llm_prefix(self) -> str:
         return "Thought:"
 
 
-@deprecated("0.1.0", removal="1.0")
+@deprecated(
+    "0.1.0",
+    message=AGENT_DEPRECATION_WARNING,
+    removal="1.0",
+)
 class DocstoreExplorer:
     """Class to assist with exploration of a document store."""
 
@@ -119,7 +128,11 @@ def _paragraphs(self) -> List[str]:
         return self.document.page_content.split("\n\n")
 
 
-@deprecated("0.1.0", removal="1.0")
+@deprecated(
+    "0.1.0",
+    message=AGENT_DEPRECATION_WARNING,
+    removal="1.0",
+)
 class ReActTextWorldAgent(ReActDocstoreAgent):
     """Agent for the ReAct TextWorld chain."""
 
@@ -139,7 +152,11 @@ def _validate_tools(cls, tools: Sequence[BaseTool]) -> None:
             raise ValueError(f"Tool name should be Play, got {tool_names}")
 
 
-@deprecated("0.1.0", removal="1.0")
+@deprecated(
+    "0.1.0",
+    message=AGENT_DEPRECATION_WARNING,
+    removal="1.0",
+)
 class ReActChain(AgentExecutor):
     """[Deprecated] Chain that implements the ReAct paper."""