Pass kwargs from initialize_agent into agent classmethod

langchain/agents/initialize.py

@@ -51,7 +51,7 @@ def initialize_agent(
             )
         agent_cls = AGENT_TO_CLASS[agent]
         agent_obj = agent_cls.from_llm_and_tools(
-            llm, tools, callback_manager=callback_manager
+            llm, tools, callback_manager=callback_manager, **kwargs
         )
     elif agent_path is not None:
         agent_obj = load_agent(

tests/unit_tests/agents/test_agent.py

@@ -196,3 +196,30 @@ def test_agent_tool_return_direct() -> None:
 
     output = agent.run("when was langchain made")
     assert output == "misalignment"
+
+
+def test_agent_with_new_prefix_suffix() -> None:
+    """Test agent initilization kwargs with new prefix and suffix."""
+    fake_llm = FakeListLLM(
+        responses=["FooBarBaz\nAction: Search\nAction Input: misalignment"]
+    )
+    tools = [
+        Tool("Search", lambda x: x, "Useful for searching", return_direct=True),
+    ]
+    prefix = "FooBarBaz"
+
+    suffix = "Begin now!\nInput: {input}\nThought: {agent_scratchpad}"
+
+    agent = initialize_agent(
+        tools=tools,
+        llm=fake_llm,
+        agent="zero-shot-react-description",
+        prefix=prefix,
+        suffix=suffix,
+    )
+
+    # avoids "BasePromptTemplate" has no attribute "template" error
+    assert hasattr(agent.agent.llm_chain.prompt, "template")
+    prompt_str = agent.agent.llm_chain.prompt.template
+    assert prompt_str.startswith(prefix), "Prompt does not start with prefix"
+    assert prompt_str.endswith(suffix), "Prompt does not end with suffix"