studying harnesses like codex inside out is low key one of the best investments you can make if you want to get better at working with llms
sadly models usually don't really understand their own harnesses or how to use them effectively. for example, codex and claude both have very little idea how to drive codex exec or claude -p correctly. i've tried getting them to do it many times
if you understand how the harness and its tools actually work, you gain a lot more control over them. you also develop a better vocabulary for driving them, which makes it much easier to steer the agent toward the outcome you actually want
most models don't even know about some of the tools that are installed by default unless you explicitly guide them to use those tools