No. āHe disguised as a CIA agent.ā is wrong. You need an object, or you need āisā before the adjective.
Some past participle (passive) forms are also adjectives. āDisguisedā is one. Is that whatās confusing? Look at these examples. Can you see which sentence uses an adjective?
Helen was having a bad day. She was cold, she was hungry and she was disguised as a CIA agent.
Helen was disguised by her sister, who was a Hollywood make-up artist.
This chicken is delicious. Was it cooked in the oven?
Is the chicken cooked? Iām starving.
The walls in my apartment are all painted. I donāt like wallpaper.
Jim does the plumbing, Matt does the electrics and any walls are painted by Bob.
The street is closed on Mondays for a street market.
I canāt buy any vegetables because the shopās closed.
āIf horrific was pronounced āorrificā and historic was pronounced āistoricā then it would be appropriate to refer to āan istoric occasionā or āan orrific accidentā. In the 18th and 19th centuries, people often did pronounce these words in this way.ā
āder gefangene Spionā and ādie gestorbene Mutterā
If ādisguiseā is a transitive verb, like āfangenā in German, its past particle form will have a passive meaning. But in āa CIA agent disguised as an English teacher,ā It seems that ādisguisedā has only the meaning related to the perfect tense. This is why I feel the expression is strange.
The past particle form of sterben, āgestorbene,ā does not have a passive meaning. It is only related to the perfect tense in meaning. āSterbenā in German is an intransitive verb.
You appear to be an expert in European languages who is disguised as a student of English
I deleted an earlier contribution because it didnāt make much sense (which is sooo unusual for my comments).