Awesome List of resources on Agile Software Development.
Could a “Definition of Ready” Help You Strike a Balance? - by Sandy Mamoli. “The definition of ready is a working agreement for the team that states what a story must have to be considered ready to to be pulled into a sprint.”
The Dangers of a Definition of Ready - by Mike Cohn. “To use a Definition of Ready successfully, you should avoid including rules that require something be 100 percent done before a story is allowed into the iteration—with the possible exception of dependencies on certain teams or vendors. Further, favor guidelines rather than rules on your Definition of Ready.”