diff --git a/pinecone/async_client/async_index.py b/pinecone/async_client/async_index.py
index a19db0d6..ecce9209 100644
--- a/pinecone/async_client/async_index.py
+++ b/pinecone/async_client/async_index.py
@@ -625,7 +625,7 @@ async def query_namespaces(
         """
         if not namespaces:
             raise ValidationError("namespaces must be a non-empty list")
-        if not vector and not sparse_vector:
+        if (vector is None or len(vector) == 0) and not sparse_vector:
             raise ValidationError("at least one of 'vector' or 'sparse_vector' must be provided")
 
         valid_metrics = {"cosine", "euclidean", "dotproduct"}
diff --git a/pinecone/index/__init__.py b/pinecone/index/__init__.py
index 43abb09a..102c4a9b 100644
--- a/pinecone/index/__init__.py
+++ b/pinecone/index/__init__.py
@@ -736,7 +736,7 @@ def query_namespaces(
         """
         if not namespaces:
             raise ValidationError("namespaces must be a non-empty list")
-        if not vector and not sparse_vector:
+        if (vector is None or len(vector) == 0) and not sparse_vector:
             raise ValidationError("at least one of 'vector' or 'sparse_vector' must be provided")
 
         valid_metrics = {"cosine", "euclidean", "dotproduct"}
diff --git a/tests/unit/test_async_query_namespaces.py b/tests/unit/test_async_query_namespaces.py
index 38cf7241..7a4d8d0c 100644
--- a/tests/unit/test_async_query_namespaces.py
+++ b/tests/unit/test_async_query_namespaces.py
@@ -15,6 +15,20 @@
 INDEX_HOST = "test-index-abc1234.svc.us-east1-gcp.pinecone.io"
 
 
+class _BoolAmbiguousVector:
+    def __init__(self, values: list[float]) -> None:
+        self._values = values
+
+    def __len__(self) -> int:
+        return len(self._values)
+
+    def __getitem__(self, index: int) -> float:
+        return self._values[index]
+
+    def __bool__(self) -> bool:
+        raise ValueError("truth value is ambiguous")
+
+
 def _make_index() -> AsyncIndex:
     return AsyncIndex(host=INDEX_HOST, api_key="test-key")
 
@@ -103,6 +117,23 @@ async def test_query_namespaces_empty_vector_raises(self) -> None:
                 metric="cosine",
             )
 
+    @pytest.mark.asyncio
+    async def test_query_namespaces_does_not_bool_check_vector(self) -> None:
+        idx = _make_index()
+        response = _make_query_response([_scored("v1", 0.9)])
+        vector = _BoolAmbiguousVector([0.1, 0.2])
+
+        mock_query = AsyncMock(return_value=response)
+        with patch.object(idx, "query", mock_query):
+            await idx.query_namespaces(
+                vector=vector,
+                namespaces=["ns1"],
+                metric="cosine",
+            )
+
+        assert mock_query.await_count == 1
+        assert mock_query.call_args.kwargs["vector"] is vector
+
     @pytest.mark.asyncio
     async def test_query_namespaces_invalid_metric_raises(self) -> None:
         idx = _make_index()
diff --git a/tests/unit/test_query_namespaces.py b/tests/unit/test_query_namespaces.py
index 6e642ead..7265bec3 100644
--- a/tests/unit/test_query_namespaces.py
+++ b/tests/unit/test_query_namespaces.py
@@ -16,6 +16,20 @@
 INDEX_HOST = "test-index-abc1234.svc.us-east1-gcp.pinecone.io"
 
 
+class _BoolAmbiguousVector:
+    def __init__(self, values: list[float]) -> None:
+        self._values = values
+
+    def __len__(self) -> int:
+        return len(self._values)
+
+    def __getitem__(self, index: int) -> float:
+        return self._values[index]
+
+    def __bool__(self) -> bool:
+        raise ValueError("truth value is ambiguous")
+
+
 def _make_index() -> Index:
     return Index(host=INDEX_HOST, api_key="test-key")
 
@@ -137,6 +151,21 @@ def test_query_namespaces_empty_vector_raises(self) -> None:
                 metric="cosine",
             )
 
+    def test_query_namespaces_does_not_bool_check_vector(self) -> None:
+        idx = _make_index()
+        response = _make_query_response([_scored("v1", 0.9)])
+        vector = _BoolAmbiguousVector([0.1, 0.2])
+
+        with patch.object(idx, "query", return_value=response) as mock_query:
+            idx.query_namespaces(
+                vector=vector,
+                namespaces=["ns1"],
+                metric="cosine",
+            )
+
+        assert mock_query.call_count == 1
+        assert mock_query.call_args.kwargs["vector"] is vector
+
     def test_query_namespaces_no_vector_no_sparse_raises(self) -> None:
         idx = _make_index()
         with pytest.raises(