I don't think there is any algorithm for detecting design, in spite of what ID claims.
However, clues that an object may be designed are
- it closely resembles something we know is designed. If we see something ancient that contains what looks like writing, there's a good chance it was designed.
- There is evidence that design and construction work has been done, e.g. plans, blueprints.
- We do not believe it could have arisen through natural processes alone
- it appears to have a function that would benefit a potential designer.
If we look at life against these criteria
- life does not closely resemble things we know are designed. We have not so far designed anything like it. In a few years maybe we will. It does resemble designed things in terms of complexity, but that is pretty vague.
- The only plans and Blueprints we have are religious texts.
- Life could have developed through natural processes, provided we accept that small step-wise changes were possible at every point. The big failure of ID is to ignore the viability of intermediates between the starting point and the end point. Increasingly evidence suggests that intermediate steps are viable.
- Life appears to have no function other than to potentially please a designer!