Perhaps this will help. According to Google's Ngrams site, "provocateur" appears in books dating before 1915.

I see this word without "Agent" used in "Testimony of Alexander Orlov" in 1862, page 6, TEXT, "The name of this provocateur is Mark."

https://books.google.com/ngrams/graph?content=+provocateur&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t1%3B%2Cprovocateur%3B%2Cc0

Perhaps this will help. According to Google's Ngram site, "provocateur" appears in books dating before 1915.

I see this word without "Agent" used in "Testimony of Alexander Orlov" in 1862, page 6:

"The name of this provocateur is Mark."