diff --git a/lib/glueby/internal/wallet.rb b/lib/glueby/internal/wallet.rb
index 16f99fe..157f003 100644
--- a/lib/glueby/internal/wallet.rb
+++ b/lib/glueby/internal/wallet.rb
@@ -94,6 +94,8 @@ def tokens(color_id = nil, only_finalized = true, page = 1, per = 25)
       end
 
       # @param color_id [Tapyrus::Color::ColorIdentifier] The color identifier associated with UTXO.
+      #                    It will return only UTXOs with specified color_id. If color_id is nil, it will return all UTXOs.
+      #                    If Tapyrus::Color::ColorIdentifier.default is specified, it will return uncolored UTXOs(i.e. TPC)
       # @param only_finalized [Boolean] The flag to get a UTXO with status only finalized
       # @param label [String] This label is used to filtered the UTXOs with labeled if a key or Utxo is labeled.
       #                    - If label is nil or :unlabeled, only unlabeled UTXOs will be returned.
diff --git a/lib/glueby/internal/wallet/abstract_wallet_adapter.rb b/lib/glueby/internal/wallet/abstract_wallet_adapter.rb
index f09e5de..00c840f 100644
--- a/lib/glueby/internal/wallet/abstract_wallet_adapter.rb
+++ b/lib/glueby/internal/wallet/abstract_wallet_adapter.rb
@@ -68,7 +68,9 @@ def balance(wallet_id, only_finalized = true)
         # Returns all tokens with specified color_id
         #
         # @param [String] wallet_id - The wallet id that is offered by `create_wallet()` method.
-        # @param [String] color_id - The color id 
+        # @param [Tapyrus::Color::ColorIdentifier] color_id The color identifier associated with UTXO.
+        #                                                     It will return only UTXOs with specified color_id. If color_id is nil, it will return all UTXOs.
+        #                                                     If Tapyrus::Color::ColorIdentifier.default is specified, it will return uncolored UTXOs(i.e. TPC)
         # @param [Boolean] only_finalized - includes only finalized UTXO value if it
         #                                   is true. Default is true.
         # @param [Integer] page - The page parameter is responsible for specifying the current page being viewed within the paginated results. default is 1.
@@ -84,6 +86,7 @@ def tokens(wallet_id, color_id = nil, only_finalized = true, page = 1, per = 25)
         # @param [String] wallet_id - The wallet id that is offered by `create_wallet()` method.
         # @param [Tapyrus::Color::ColorIdentifier] color_id - The color identifier. 
         #                                                     It will return only UTXOs with specified color_id. If color_id is nil, it will return all UTXOs.
+        #                                                     If Tapyrus::Color::ColorIdentifier.default is specified, it will return uncolored UTXOs(i.e. TPC)
         # @param [Boolean] only_finalized - The UTXOs includes only finalized UTXO value if it
         #                                   is true. Default is true.
         # @param [String] label - Label for filtering UTXOs