The best places where I get this info is from the ai engineer YouTube channel and Claude’s YouTube channel.
For effective harness engineering you need to also read the detailed prompting guide for each model. We are back at a place where every model revision introduces harness optimizations that need to happen.
You seem to be doing all the right things though. The tldr is treat your agent to be a precocious kid and the job of the harness is to helicopter parent it without the kid realizing it’s being parented.