A machine tool system includes at least one portable machine tool and at least one energy storage apparatus. The at least one portable machine tool includes at least one tool receptacle configured to be arrange a machining tool, and at least one receiving interface. The at least one energy storage apparatus is configured to be arranged on the at least one receiving interface of the at least one portable machine tool. At least in a state when the at least one energy storage apparatus is arranged on the at least one receiving interface, the at least one energy storage apparatus is arranged at least for the most part within a boundary region of the at least one tool receptacle.