In these two sentences "tired" is always adjective:
I was tired.
I have been tired.
In these two sentences "told" is always part of the passive, perfect participle:
I was told.
I have been told.
How to know when is passive, when is an adjective?
Firstly, do you always need to know? If someone says "I was bored" is that an adjective or passive? It could be either.
Passive is always "(be verb) (past participle)" so
If you want to test, try using the same word in front of a noun. If it means the same, then you probably have an adjective. On the other hand if you could add a "by" phrase, then you have a passive
I was tired - I was a tired man.
That works, so tired looks like an adjective. Also "I was tired by him" is odd.
The donut was eaten. It was an eaten donut.
That's rather odd, if it's eaten then it isn't a donut anymore. That's probably a passive. You could easily add "The donut was eaten by him" and it still makes sense.
I was told - I was a told man
That doesn't work at all, it must be a passive. You can say "I was told by him"