TL;DR

• Definition of Ready (DoR) defines a agile story's “ready state”
• Considerations before an item is pulled into owned value stream
• Direct impact on the 8 Wastes of Lean
• Does not mean story is 100% defined with zero unknowns
• Summed up in a radiated checklist
• Reference Blog Post (Shameless Plug): Definition of Ready

Definition of Ready - DoR

Ideally, DoR should be applied to every unit of work entering your section of the value stream. The Scrum Agile Lean DevOps (SALD) model teaches us to optimize for downstream. Thus, if your organization is a permutation of SALD, it is fair to ask internal customers/team members to do the same.

In reality, we need to work with our customers (product owners) to create a common understanding of the minimum sufficient amount of details necessary to not waste either parties time. (Excess Processing)
'I don't have time now' directly translates into 'waste'. It explicitly implies WIP is too large. (Inventory Excess)
DoR prevents churn, misunderstandings, and bottlenecks! (Motion, Defects, Transportation, Overproduction, Waiting)
Brain surgeons don't work in reception. (Not utilizing talent)

Radiation

If you cannot directly point to your team's explicit definition of ready from your individual work space, you may not have a definition of ready...

DoR Checklist

• Value is understood
• Acceptance criteria are clear and testable
• Shared understanding within the team (NO SILOS)
• Known dependencies
• Similar features for reference
• Size is sufficiently small
• Testing effort is considered and/or discussed
• Non-functional requirements
• How to demonstrate the story's work
• Defects are reproducible with fixtures