diff --git a/langchain/model_laboratory.py b/langchain/model_laboratory.py
index e31d6654..090c8e52 100644
--- a/langchain/model_laboratory.py
+++ b/langchain/model_laboratory.py
@@ -1,9 +1,8 @@
 """Experiment with different models."""
 from __future__ import annotations
 
-from typing import List, Optional, Sequence, Union
+from typing import List, Optional, Sequence
 
-from langchain.agents.agent import Agent
 from langchain.chains.base import Chain
 from langchain.chains.llm import LLMChain
 from langchain.input import get_color_mapping, print_text
@@ -14,32 +13,29 @@ from langchain.prompts.prompt import PromptTemplate
 class ModelLaboratory:
     """Experiment with different models."""
 
-    def __init__(
-        self, chains: Sequence[Union[Chain, Agent]], names: Optional[List[str]] = None
-    ):
+    def __init__(self, chains: Sequence[Chain], names: Optional[List[str]] = None):
         """Initialize with chains to experiment with.
 
         Args:
             chains: list of chains to experiment with.
         """
         for chain in chains:
-            if not isinstance(chain, (Chain, Agent)):
+            if not isinstance(chain, Chain):
                 raise ValueError(
-                    "ModelLaboratory should now be initialized with Chains or Agents. "
+                    "ModelLaboratory should now be initialized with Chains. "
                     "If you want to initialize with LLMs, use the `from_llms` method "
                     "instead (`ModelLaboratory.from_llms(...)`)"
                 )
-            if isinstance(chain, Chain):
-                if len(chain.input_keys) != 1:
-                    raise ValueError(
-                        "Currently only support chains with one input variable, "
-                        f"got {chain.input_keys}"
-                    )
-                if len(chain.output_keys) != 1:
-                    raise ValueError(
-                        "Currently only support chains with one output variable, "
-                        f"got {chain.output_keys}"
-                    )
+            if len(chain.input_keys) != 1:
+                raise ValueError(
+                    "Currently only support chains with one input variable, "
+                    f"got {chain.input_keys}"
+                )
+            if len(chain.output_keys) != 1:
+                raise ValueError(
+                    "Currently only support chains with one output variable, "
+                    f"got {chain.output_keys}"
+                )
         if names is not None:
             if len(names) != len(chains):
                 raise ValueError("Length of chains does not match length of names.")