An IBM Rational Tools developer utilizes IBM's suite of software tools to design, develop, and manage systems. They use Rational Software Architect for designing software architectures, Rational Application Developer for building web and Java applications, and Rational Functional Tester for automating functional, regression, and GUI testing. They also use Rational ClearCase for version control and Rational ClearQuest for defect tracking. The developer uses these tools to streamline application development, ensure code quality, and enhance team collaboration. They also troubleshoot and resolve issues within the software development lifecycle, ensuring efficient and effective software delivery.