Product Backlog Items are brief descriptions of a feature or function. Usually they are short enough that they could be hand-written on a small note card. This brevity is meant to be just enough information so that the Product Owner and the team can use the PBIs as invitations to conversations. The resulting conversation (ongoing, evolving and involving the whole team and stakeholders) and the shared understanding that comes from that conversation is where the real value of the PBI resides. Part of the conversation occurs when the Product Owner initially writes the PBI so that the team can estimate the effort of building it. Part of the conversation is the actual work being done during a Sprint. Another part of the conversation is during the Sprint Review when stakeholders see the results of the team building the PBIs. If one creates PBIs as detailed specifications then we are essentially handcuffing the team into a set path and a prescriptive solution. The reason we hire qualified people onto our Scrum Team is for their knowledge, experience, and problem solving abilities. If we lock them into a set path, then we are literally turning them into cogs in a machine to spit out specific code. PBIs that are invitations to conversations allow them the flexibility to figure out how to solve the problem by engaging in a conversation on what is needed.