When i write a job in the logbook, Do I have to write the snag associated to it or just the action taken?
Lately i'v been writing the action taken merely but it looks a bit odd without the snag.

Write everything you do in your logbook!

if you have a CAP741 book the instructions for filling it out that are in it are quite good.

As Miles says, write everything, including fault finding/troubleshooting if you are an Avionic type.

Thank you all for the suggestions.