The log needs to document, at least in broad steps and critical details, what the next operation is and what key parameters were provided to it.
A human, or an 'agent' can use those to figure out why said next step might have gone wrong.
A human, or an 'agent' can use those to figure out why said next step might have gone wrong.
Also it's helpful to log before operations rather than after because if a step gets stuck it's possible to know what it's stuck on.