diff --git a/lib/sycamore/sycamore/connectors/opensearch/opensearch_reader.py b/lib/sycamore/sycamore/connectors/opensearch/opensearch_reader.py
index 3a2956c16..1e3cc5a56 100644
--- a/lib/sycamore/sycamore/connectors/opensearch/opensearch_reader.py
+++ b/lib/sycamore/sycamore/connectors/opensearch/opensearch_reader.py
@@ -1,3 +1,4 @@
+import copy
 import logging
 
 from sycamore.data import Document, Element
@@ -47,6 +48,9 @@ def read_records(self, query_params: BaseDBReader.QueryParams) -> "OpenSearchRea
         if "size" not in query_params.query and "size" not in query_params.kwargs:
             query_params.kwargs["size"] = 200
         result = []
+        # We only fetch the minimum required fields for full document retrieval/reconstruction
+        if query_params.reconstruct_document:
+           query_params.kwargs["_source_includes"] = "doc_id,parent_id,properties"
         # No pagination needed for knn queries
         if "query" in query_params.query and "knn" in query_params.query["query"]:
             response = self._client.search(
@@ -148,6 +152,8 @@ def to_docs(self, query_params: "BaseDBReader.QueryParams") -> list[Document]:
 
             # Batched retrieval of all elements belong to unique docs
             doc_ids = list(unique_docs.keys())
+            # We can't safely exclude embeddings since we might need them for 'rerank', e.g.
+            # We will need the Planner to determine that and pass that info to the reader.
             all_elements_for_docs = self._get_all_elements_for_doc_ids(doc_ids, query_params.index_name)
 
             """
@@ -183,7 +189,6 @@ def _get_all_elements_for_doc_ids(self, doc_ids: list[str], index: str) -> list[
         """
         batch_size = 100
         page_size = 500
-
         all_elements = []
         for i in range(0, len(doc_ids), batch_size):
             doc_ids_batch = doc_ids[i : i + batch_size]
diff --git a/lib/sycamore/sycamore/reader.py b/lib/sycamore/sycamore/reader.py
index e46d4a090..ff7301844 100644
--- a/lib/sycamore/sycamore/reader.py
+++ b/lib/sycamore/sycamore/reader.py
@@ -224,7 +224,7 @@ def opensearch(
         index_name: str,
         query: Optional[Dict] = None,
         reconstruct_document: bool = False,
-        query_kwargs: dict[str, Any] = {},
+        query_kwargs=None,
         **kwargs,
     ) -> DocSet:
         """
@@ -287,6 +287,8 @@ def opensearch(
             OpenSearchReaderQueryParams,
         )
 
+        if query_kwargs is None:
+            query_kwargs = {}
         client_params = OpenSearchReaderClientParams(os_client_args=os_client_args)
         query_params = (
             OpenSearchReaderQueryParams(