RealTime::Client has some information(self, team, channels, ...)

lib/slack/api.rb

@@ -23,8 +23,7 @@ def initialize(options={})
     include Endpoint
 
     def realtime
-      url = post("rtm.start")["url"]
-      RealTime::Client.new(url)
+      RealTime::Client.new(post("rtm.start"))
     end
   end
 end

lib/slack/realtime/client.rb

@@ -4,8 +4,9 @@
 module Slack
   module RealTime
     class Client
-      def initialize(url)
-        @url = url
+      def initialize(rtm_start_response)
+        @response = rtm_start_response
+        @url = rtm_start_response
         @callbacks ||= {}
       end
 
@@ -36,6 +37,16 @@ def start
           end
         end
       end
+
+      def method_missing(method, *args, &block)
+        return super if @response[method.to_s].nil?
+        @response[method.to_s]
+      end
+
+      # Delegate to Slack::Client
+      def respond_to?(method, include_all=false)
+        return !@response[method.to_s].nil? || super
+      end
     end
   end
 end