diff --git a/src/bedrock_agentcore/memory/constants.py b/src/bedrock_agentcore/memory/constants.py
index 6ab3a444..ba4687d6 100644
--- a/src/bedrock_agentcore/memory/constants.py
+++ b/src/bedrock_agentcore/memory/constants.py
@@ -157,7 +157,7 @@ class RetrievalConfig(BaseModel):
         retrieval_query: Optional custom query for semantic search (default: None)
     """
 
-    top_k: int = Field(default=10, gt=1, le=100)
+    top_k: int = Field(default=10, ge=1, le=100)
     relevance_score: float = Field(default=0.0, ge=0.0, le=1.0)
     strategy_id: Optional[str] = None
     retrieval_query: Optional[str] = None
diff --git a/tests/bedrock_agentcore/memory/test_session.py b/tests/bedrock_agentcore/memory/test_session.py
index 3108587a..d33cafcc 100644
--- a/tests/bedrock_agentcore/memory/test_session.py
+++ b/tests/bedrock_agentcore/memory/test_session.py
@@ -3940,3 +3940,17 @@ def test_get_last_k_turns_explicit_max_results(self):
             manager.get_last_k_turns(actor_id="user-123", session_id="session-456", k=200, max_results=50)
             call_kwargs = manager._data_plane_client.list_events.call_args[1]
             assert call_kwargs["maxResults"] == 50
+
+
+def test_retrieval_config_top_k_allows_one():
+    """top_k=1 (single best-scoring record) is valid; the SDK itself calls
+    retrieve_memories(top_k=1). The lower bound must be inclusive (ge=1)."""
+    import pytest as _pytest
+    from pydantic import ValidationError
+
+    assert RetrievalConfig(top_k=1).top_k == 1  # must not raise
+    # bounds still enforced on either side
+    with _pytest.raises(ValidationError):
+        RetrievalConfig(top_k=0)
+    with _pytest.raises(ValidationError):
+        RetrievalConfig(top_k=101)