Ideas to use in resolving an issue with regard to personal productivity. Often used to increase effectiveness or efficiency.
A tool is a device that can be used to produce an item or achieve a task, but that is not consumed in the process. Informally the word is also used to describe a procedure or process with a specific purpose. Tools that are used in particular fields or activities may have different designations such as Instrument, Utensil, Implement, Machine, or Apparatus.
Generally this can be around various perspectives to have in GTD or improving a process one uses.