diff --git a/src/bedrock_agentcore/evaluation/custom_code_based_evaluators/models.py b/src/bedrock_agentcore/evaluation/custom_code_based_evaluators/models.py
index 7d17b1cf..c876b145 100644
--- a/src/bedrock_agentcore/evaluation/custom_code_based_evaluators/models.py
+++ b/src/bedrock_agentcore/evaluation/custom_code_based_evaluators/models.py
@@ -82,7 +82,6 @@ class EvaluatorOutput(BaseModel):
     def _require_label_or_error_code(self) -> "EvaluatorOutput":
         if not self.errorCode and self.label is None:
             raise ValueError(
-                "Either label, value, or errorCode must be set; "
-                "set errorCode to return an error response without a label"
+                "label is required for success responses; set errorCode to return an error response without a label"
             )
         return self
diff --git a/src/bedrock_agentcore/evaluation/integrations/strands_agents_evals/README.md b/src/bedrock_agentcore/evaluation/integrations/strands_agents_evals/README.md
index 3f41931c..adf67656 100644
--- a/src/bedrock_agentcore/evaluation/integrations/strands_agents_evals/README.md
+++ b/src/bedrock_agentcore/evaluation/integrations/strands_agents_evals/README.md
@@ -83,8 +83,7 @@ evaluator = create_strands_evaluator("Builtin.Helpfulness")
 
 # Run evaluations
 experiment = Experiment(cases=cases, evaluators=[evaluator])
-reports = experiment.run_evaluations(task_fn)
-report = reports[0]
+report = experiment.run_evaluations(task_fn)
 
 # View results
 print(f"Overall score: {report.overall_score:.2f}")
@@ -175,8 +174,7 @@ def task_fn(case):
 
 evaluator = create_strands_evaluator("Builtin.Helpfulness")
 experiment = Experiment(cases=cases, evaluators=[evaluator])
-reports = experiment.run_evaluations(task_fn)
-report = reports[0]
+report = experiment.run_evaluations(task_fn)
 
 print(f"Overall score: {report.overall_score:.2f}")
 ```
diff --git a/tests/bedrock_agentcore/evaluation/integrations/strands_agents_evals/test_end_to_end.py b/tests/bedrock_agentcore/evaluation/integrations/strands_agents_evals/test_end_to_end.py
index 1da6ceb6..d426cffa 100644
--- a/tests/bedrock_agentcore/evaluation/integrations/strands_agents_evals/test_end_to_end.py
+++ b/tests/bedrock_agentcore/evaluation/integrations/strands_agents_evals/test_end_to_end.py
@@ -65,8 +65,7 @@ def task_fn(case):
         with patch("boto3.client", return_value=mock_boto_client):
             evaluator = create_strands_evaluator("Builtin.Helpfulness")
             experiment = Experiment(cases=cases, evaluators=[evaluator])
-            reports = experiment.run_evaluations(task_fn)
-            report = reports[0]
+            report = experiment.run_evaluations(task_fn)
 
             # Should return 0 score for empty trajectory
             assert report.overall_score == 0.0
diff --git a/tests/bedrock_agentcore/memory/integrations/strands/test_agentcore_memory_session_manager.py b/tests/bedrock_agentcore/memory/integrations/strands/test_agentcore_memory_session_manager.py
index fa0c4787..b225cfa9 100644
--- a/tests/bedrock_agentcore/memory/integrations/strands/test_agentcore_memory_session_manager.py
+++ b/tests/bedrock_agentcore/memory/integrations/strands/test_agentcore_memory_session_manager.py
@@ -3722,9 +3722,13 @@ def test_async_mode_registers_multi_agent_callbacks(self, mock_memory_client):
         registry = HookRegistry()
         manager.register_hooks(registry)
 
-        for event_type in (MultiAgentInitializedEvent, AfterNodeCallEvent, AfterMultiAgentInvocationEvent):
-            callbacks = registry._registered_callbacks.get(event_type, [])
-            assert callbacks, f"No callbacks registered for {event_type.__name__}"
+        for event in (
+            MultiAgentInitializedEvent(source=Mock()),
+            AfterNodeCallEvent(source=Mock(), node_id="n1"),
+            AfterMultiAgentInvocationEvent(source=Mock()),
+        ):
+            callbacks = list(registry.get_callbacks_for(event))
+            assert callbacks, f"No callbacks registered for {type(event).__name__}"
             assert all(asyncio.iscoroutinefunction(cb) for cb in callbacks)
 
     def test_async_mode_logs_sync_invocation_warning(self, mock_memory_client, caplog):
@@ -3746,15 +3750,18 @@ def test_async_mode_registers_bidi_agent_callbacks(self, mock_memory_client):
         manager.register_hooks(registry)
 
         # BidiAgentInitializedEvent dispatches via the sync hook path, so its callback must NOT be a coroutine.
-        init_callbacks = registry._registered_callbacks.get(BidiAgentInitializedEvent, [])
+        init_callbacks = list(registry.get_callbacks_for(BidiAgentInitializedEvent(agent=Mock())))
         assert init_callbacks, "No callbacks registered for BidiAgentInitializedEvent"
         assert not any(asyncio.iscoroutinefunction(cb) for cb in init_callbacks)
 
         # BidiMessageAddedEvent and BidiAfterInvocationEvent dispatch via invoke_callbacks_async,
         # so their callbacks should be async to keep the event loop unblocked.
-        for event_type in (BidiMessageAddedEvent, BidiAfterInvocationEvent):
-            callbacks = registry._registered_callbacks.get(event_type, [])
-            assert callbacks, f"No callbacks registered for {event_type.__name__}"
+        for event in (
+            BidiMessageAddedEvent(agent=Mock(), message={"role": "user", "content": [{"text": "x"}]}),
+            BidiAfterInvocationEvent(agent=Mock()),
+        ):
+            callbacks = list(registry.get_callbacks_for(event))
+            assert callbacks, f"No callbacks registered for {type(event).__name__}"
             assert all(asyncio.iscoroutinefunction(cb) for cb in callbacks)