Nowadays service creation and consumption is an ordinary, everyday task. Although services are commonly associated to a server -in a fixed machine on the Web- at present services may also be offered from portable devices (i.e., PDAs, smartphones, etc.). Both service provider's and users' mobility requires a highly dynamic service usage, thus bringing about the necessity to develop and use services in mobile environments. This article addresses the problems arising when designing interfaces for service creation and consumption on mobile devices, taking into account different aspects as those concerning the reduced screen size of those devices. This is a key aspect since the user should be capable of providing a sound and complete definition of the logic of a service. In this work a new paradigm is presented for service creation using natural written language. This paradigm has been developed so that the said service design can be performed from the mobile terminal itself, enabling utilization by non-experienced users and aiming at obtaining new service definitions which can be easily publishable and shareable.