This is getting kind of annoying now. Everytime i am planned for a (small) project, there is less to no briefing and nobody has a clue what to do.
Then how the hell am i supposed to?

Been there. Use ctrl+f to find actual implementation because no one knew or wanted to share it with me, tried a lot of changes, tested them thoroughly, then comes comments like "we didn't want that".

Really? Then what did you want? Do I need to do a psych profile of you to make it out of thin air? Cause I can. And the result you won't like it.

It is important to have a plan. Many projects do not and many fail. Failing to plan, is planning to fail.