program selection system

What do you see as the biggest issue for Functional Testing Tools on Agile Projects

Is there is a need to have a functional test tool on non UI components such as web services, or various APIs that would serve to both customers, developers, quality engineers and testers? Should there be one tool that fits all needs or should there be multiple? Are there tools that are easily re factored depending on the implementation of web services - should there be? I always find myself writing the frameworks to do that myself.

What do you hope to contribute?