Prototyping is an effective and efficient way of requirement validation to avoid introducing errors in the early stage of software development. Our previous work RM2PT can automatically generating prototypes from requirements models to support incremental and rapid requirements validation. Although the stakeholders can validate requirements through executing the system operations of the generated prototype, the input parameters of system operations still need to be manually typed by the stakeholders. Unlike software testing, the input of system operation must be validated and reasonable for the stakeholders under the specific scenario of use case. This is usually hard to be achieved by the stakeholders who have less knowledge and concern about the state and interface of target system. In this paper, we propose a tool InputGen, which can automatically refactor and enhanced the generated prototype from RM2PT. The enhanced prototype can automatically generate a validated input data of the system operations for requirement validation. In addition, the enhanced prototype provide an external interface to load the initial data from a external file, which can save the time of modeling the data functionality for the administrator. We demonstrate that the enhanced prototype can improve 56.43% times efficiency of requirements validation than the original generated prototype from RM2PT. Overall, the results were satisfactory. The proposed tool can be further extended and applied for the requirements validation in the software industry. The tool can be downloaded at https://rm2pt.com/advs/inputgen, and a demo video casting its features is at https://youtu.be/iR_ojHyzDvQ.