Before creating something new, look at what is already there. Observe or measure services and methods at first hand to see how they stand now and what could be reused; take data from the source, since reports and reality drift apart; let outsiders ask naive questions; use measurement to back up observation, not replace it (a measure turned into a target stops being a good measure); view what exists objectively from the standpoint of the outcome the customer wants; copy and extend practices that work; apply risk management both to reusing and to replacing; and accept that occasionally nothing is reusable.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.