diff --git a/metagpt/exp_pool/context_builders/action_node.py b/metagpt/exp_pool/context_builders/action_node.py
index a3362875c..891b898be 100644
--- a/metagpt/exp_pool/context_builders/action_node.py
+++ b/metagpt/exp_pool/context_builders/action_node.py
@@ -24,6 +24,7 @@ class ActionNodeContextBuilder(BaseContextBuilder):
         If there are no experiences, returns the original `req`;
         otherwise returns context with `req` and formatted experiences.
         """
+
         exps = self.format_exps()
 
         return ACTION_NODE_CONTEXT_TEMPLATE.format(req=req, exps=exps) if exps else req
diff --git a/metagpt/exp_pool/context_builders/role_zero.py b/metagpt/exp_pool/context_builders/role_zero.py
index 2ee469661..aa5524ab4 100644
--- a/metagpt/exp_pool/context_builders/role_zero.py
+++ b/metagpt/exp_pool/context_builders/role_zero.py
@@ -16,6 +16,7 @@ class RoleZeroContextBuilder(BaseContextBuilder):
             2. Returns the original `req` if it is empty, incorrectly formatted or there are no experiences.
             3. Creates a copy of req and replaces the example content in the copied req with actual experiences.
         """
+
         if not req or len(req) < 2:
             return req
 
diff --git a/metagpt/exp_pool/manager.py b/metagpt/exp_pool/manager.py
index ba1a8bcf0..d6922ff00 100644
--- a/metagpt/exp_pool/manager.py
+++ b/metagpt/exp_pool/manager.py
@@ -39,7 +39,7 @@ class ExperienceManager(BaseModel):
                     similarity_top_k=DEFAULT_SIMILARITY_TOP_K,
                 )
             ]
-            ranker_configs = [LLMRankerConfig()]
+            ranker_configs = [LLMRankerConfig(top_n=DEFAULT_SIMILARITY_TOP_K)]
 
             self.storage = SimpleEngine.from_objs(retriever_configs=retriever_configs, ranker_configs=ranker_configs)
 
@@ -57,6 +57,7 @@ class ExperienceManager(BaseModel):
         Args:
             exp (Experience): The experience to add.
         """
+
         if not self.config.exp_pool.enable_write:
             return
 
@@ -74,6 +75,7 @@ class ExperienceManager(BaseModel):
         Returns:
             list[Experience]: A list of experiences that match the args.
         """
+
         if not self.config.exp_pool.enable_read:
             return []
 
@@ -90,6 +92,8 @@ class ExperienceManager(BaseModel):
         return exps
 
     def get_exps_count(self) -> int:
+        """Get the total number of experiences."""
+
         return self.vector_store._collection.count()
 
 
diff --git a/metagpt/exp_pool/scorers/simple.py b/metagpt/exp_pool/scorers/simple.py
index fd7b6537b..4b060aac4 100644
--- a/metagpt/exp_pool/scorers/simple.py
+++ b/metagpt/exp_pool/scorers/simple.py
@@ -57,6 +57,7 @@ class SimpleScorer(BaseScorer):
         Returns:
             Score: An object containing the score (1-10) and the reasoning.
         """
+
         prompt = SIMPLE_SCORER_TEMPLATE.format(req=req, resp=resp)
         resp = await self.llm.aask(prompt)
         resp_json = json.loads(CodeParser.parse_code(resp, lang="json"))
diff --git a/metagpt/exp_pool/serializers/role_zero.py b/metagpt/exp_pool/serializers/role_zero.py
index f5363b1ff..720bf5078 100644
--- a/metagpt/exp_pool/serializers/role_zero.py
+++ b/metagpt/exp_pool/serializers/role_zero.py
@@ -24,6 +24,7 @@ class RoleZeroSerializer(SimpleSerializer):
         Returns:
             str: The serialized request as a JSON string.
         """
+
         if not req:
             return ""