Fix breaking tags (#6765)

Fix tags change that broke old way of initializing agent

Closes #6756

langchain/agents/initialize.py

@@ -51,7 +51,7 @@ def initialize_agent(
                 f"Got unknown agent type: {agent}. "
                 f"Valid types are: {AGENT_TO_CLASS.keys()}."
             )
-        tags_.append(agent.value)
+        tags_.append(agent.value if isinstance(agent, AgentType) else agent)
         agent_cls = AGENT_TO_CLASS[agent]
         agent_kwargs = agent_kwargs or {}
         agent_obj = agent_cls.from_llm_and_tools(

tests/unit_tests/agents/test_initialize.py

@@ -0,0 +1,23 @@
+"""Test the initialize module."""
+
+from langchain.agents.agent_types import AgentType
+from langchain.agents.initialize import initialize_agent
+from langchain.tools.base import tool
+from tests.unit_tests.llms.fake_llm import FakeLLM
+
+
+@tool
+def my_tool(query: str) -> str:
+    """A fake tool."""
+    return "fake tool"
+
+
+def test_initialize_agent_with_str_agent_type() -> None:
+    """Test initialize_agent with a string."""
+    fake_llm = FakeLLM()
+    agent_executor = initialize_agent(
+        [my_tool], fake_llm, "zero-shot-react-description"  # type: ignore
+    )
+    assert agent_executor.agent._agent_type == AgentType.ZERO_SHOT_REACT_DESCRIPTION
+    assert isinstance(agent_executor.tags, list)
+    assert "zero-shot-react-description" in agent_executor.tags