diff --git a/bigchaindb/backend/query.py b/bigchaindb/backend/query.py
index 0f746132..6f76249b 100644
--- a/bigchaindb/backend/query.py
+++ b/bigchaindb/backend/query.py
@@ -148,7 +148,8 @@ def get_spending_transactions(connection, inputs):
         inputs (list): list of {txid, output}
 
     Returns:
-        List of transactions that spend given inputs
+        Iterator of (block_ids, transaction) for transactions that
+        spend given inputs.
     """
     raise NotImplementedError
 
@@ -161,9 +162,9 @@ def get_owned_ids(connection, owner):
         owner (str): base58 encoded public key.
 
     Returns:
-        A cursor for the matching transactions.
+        Iterator of (block_id, transaction) for transactions
+        that list given owner in conditions.
     """
-
     raise NotImplementedError
 
 
@@ -205,7 +206,7 @@ def get_votes_for_blocks_by_voter(connection, block_ids, pubkey):
         pubkey (str): public key of voting node
 
     Returns:
-        A cursor of votes matching given votes.
+        A cursor of votes matching given block_ids and public key
     """
     raise NotImplementedError
 
diff --git a/bigchaindb/fastquery.py b/bigchaindb/fastquery.py
index a7147722..deffabe1 100644
--- a/bigchaindb/fastquery.py
+++ b/bigchaindb/fastquery.py
@@ -4,24 +4,27 @@ from bigchaindb.common.transaction import TransactionLink
 
 
 class FastQuery:
-
     """
     Database queries that join on block results from a single node.
 
-    * Votes are not validated for security (security is replication concern)
-    * Votes come from only one node, and as such, fault tolerance is reduced
+    * Votes are not validated for security (security is a replication concern)
+    * Votes come from only one node, and as such, non-byzantine fault tolerance
+      is reduced.
 
-    In return, these queries offer good performance, as it is not neccesary to validate
-    each result separately.
+    Previously, to consider the status of a block, all votes for that block
+    were retrieved and the election results were counted. This meant that a
+    faulty node may still have been able to obtain a correct election result.
+    However, from the point of view of a client, it is still neccesary to
+    query multiple nodes to insure against getting an incorrect response from
+    a byzantine node.
     """
-
     def __init__(self, connection, me):
         self.connection = connection
         self.me = me
 
     def filter_block_ids(self, block_ids, include_undecided=True):
         """
-        Given block ids, filter the invalid blocks
+        Given block ids, filter the invalid blocks.
         """
         block_ids = list(set(block_ids))
         votes = query.get_votes_for_blocks_by_voter(