When programming in Kotlin, the tool box should include an Integrated Development Environment (IDE) such as IntelliJ IDEA, Atom, Visual Studio Code, Sublime Text, or Eclipse IDE. Additionally, you should have Gradle and Maven as build systems to build software from Kotlin code, as well as access to various libraries and frameworks like Spring, JetBrains, Gradle, Spark Java, and Codename One. Finally, you may find it useful to have a debugger tool such as KDBG or LLDB to debug Kotlin programs.