diff --git a/libs/langchain/langchain/chains/rl_chain/pick_best_chain.py b/libs/langchain/langchain/chains/rl_chain/pick_best_chain.py
index 1155d03a1b..34fc3584f5 100644
--- a/libs/langchain/langchain/chains/rl_chain/pick_best_chain.py
+++ b/libs/langchain/langchain/chains/rl_chain/pick_best_chain.py
@@ -67,7 +67,7 @@ class PickBestFeatureEmbedder(base.Embedder[PickBestEvent]):
         self.auto_embed = auto_embed
 
     @staticmethod
-    def _str(embedding):
+    def _str(embedding: List[float]):
         return " ".join([f"{i}:{e}" for i, e in enumerate(embedding)])
 
     def get_label(self, event: PickBestEvent) -> tuple:
@@ -137,7 +137,7 @@ class PickBestFeatureEmbedder(base.Embedder[PickBestEvent]):
         context_matrix = np.stack([v for k, v in context_embeddings.items()])
         dot_product_matrix = np.dot(context_matrix, action_matrix.T)
 
-        indexed_dot_product = {}
+        indexed_dot_product: Dict[Dict] = {}
 
         for i, context_key in enumerate(context_embeddings.keys()):
             indexed_dot_product[context_key] = {}
@@ -167,8 +167,8 @@ class PickBestFeatureEmbedder(base.Embedder[PickBestEvent]):
                     nsa.append(ns_a)
                     for k, v in indexed_dot_product.items():
                         dot_prods.append(v[ns_a])
-                nsa = " ".join(nsa)
-                line_parts.append(f"|# {nsa}")
+                nsa_str = " ".join(nsa)
+                line_parts.append(f"|# {nsa_str}")
 
             line_parts.append(f"|dotprod {self._str(dot_prods)}")
             action_lines.append(" ".join(line_parts))
@@ -182,8 +182,8 @@ class PickBestFeatureEmbedder(base.Embedder[PickBestEvent]):
                 for elem in elements:
                     shared.append(f"{elem}")
                     nsc.append(f"{ns}={elem}")
-                nsc = " ".join(nsc)
-                shared.append(f"|@ {nsc}")
+                nsc_str = " ".join(nsc)
+                shared.append(f"|@ {nsc_str}")
 
         return "shared " + " ".join(shared) + "\n" + "\n".join(action_lines)