My personal threshold for AGI is literally: discover something new and significant in science (preferably biology) that is almost certainly true by describing an experiment that could be replicated by a large number of scientists and whose interpretation is unambiguous.
For example, the Hershey/Chase and Avery/McCleod experiments convinced the entire biological community that DNA, not protein, was almost certainly the primary molecular structure by which heredity is transferred. The experiments had the advantage of being fairly easy to understand, easy to replicate, and fairly convincing.
There are probably similar simple experiments that can be easily reproduced widely that would resolve any number of interesting questions outstanding in the field. For example, I'd like to see better ways of demonstrating the causal nature of the genome on the heredity of height, or answering a few important open questions in biology.
Right now discovery science is a chaotic, expensive, stochastic process which fails the vast majority of the time and even when it succeeds, usually only makes small incremental discoveries or slightly reduces the ambiguity of experiment's results. Most of the ttime is spent simply mastering boring technical details like how to eliminate variables (Jacob and Monod made their early discoveries in gene regulation because they were just a bit better at maintaining sterile cultures than their competitors, which allowed them to conceive of good if obvious hypotheses quickly, and verify them.