I'd like to know whether a task must be self contained.
Our tasks mostly contain a couple of sentences.
To understand what you are to do you should:
- Read the requirements document for several related back log items.
- Know how system currently works and understand how it differs from what is required.
In other words: newcomer or the person who was absent at the planning meeting will require a sufficient amount of time just to comprehend the task.
In addition such way of keeping backlog does not tell much about system evolution and looks more like a primitive contextually conditioned to-do list.