Design is something we recognise if, in decreasing order of warrant:
1. We know the intentions and plan of the designer, or can reasonably infer it from context and a knowledge of the culture of the designer
2. We see evidence that the object was manufactured in a way not found in ordinary natural processes
3. If the object is a solution to a problem of means.
Complexity is not evidence of design because some designs are very simple (Corbousier), and because some undesigned things are very complex.
Life is not recognisable as design because we do not know 1, do not see 2, and have no way of knowing 3.
Quoted from: John Wilkins Philosopher of Science (biology)
I forgot to add my contribution.
Specificity can only be determined if we know (1).