Firefox OS App developers can use Firefox Remote Debugger to quickly fix web app bugs. In this screencast Jeff Griffiths shows the current workflow of using the Firefox OS simulator and the Firefox Nightly remote debugger developer tool.
Don't see the embedded video, you can watch it on YouTube.
You can also use Firefox Remote Debugger with Firefox OS running in a desktop emulator, on a Firefox OS device and Firefox Mobile on Android mobile phone. Head over to Mozilla Developer Network (MDN) to learn more about Firefox Remote Debugging.