From the published version of Hugh B. Brown's speech given at BYU October 4, 1955:
"...the following characteristics should distinguish a man who claims to be a prophet.
A. He will boldly claim that God [has] spoken to him.
B. Any man so claiming would be a dignified man with a dignified message; no table-jumping, no whisperings from the dead, no clairvoyance, but an intelligent statement of truth.
C. Any man claiming to be a prophet of God would declare his message without any fear and without making any weak concessions to public opinion.
D. If he were speaking for God, he could not make concessions although what he taught would be new and contrary to the accepted teachings of the day. A prophet bears witness to what he has seen and heard and seldom tries to make a case by argument. His message and not himself is important.
E. Such a man would speak in the name of the Lord, saying, 'Thus saith the Lord,' as did Moses, Joshua, and others.
F. Such a man would predict future events in the name of the Lord, and they would come to pass, as did Isaiah and Ezekiel.
G. He would have not only an important message for his time but often a message for all future time, such as Daniel, Jeremiah, and others had.
H. He would have courage and faith enough to endure persecution and to give his life, if need be, for the cause he espoused, such as Peter, Paul, and others did.
I. Such a man would denounce wickedness fearlessly. He would generally be rejected or persecuted by the people of his time, but later generations, the descendants of his persecutors, would build monuments in his honor.
J. He would be able to do superhuman things, things that no man could do without God's help. The consequence or result of his message and work would be convincing evidence of his prophetic calling. 'By their fruits ye shall know them' [Matt. 7:20].
K. His teachings would be in strict conformity with scripture, and his words and his writings would become scripture. 'For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost' (2 Pet. 1:21)."
How many today fit these criteria?
One could improve this list as follows:
1) God is the source of and culmination of reason. As such, those servants closest to him are capable of and will strive to exercise persuasion to the greatest of their ability. They will, in fact, try to make their case by argument (see 'D' above).
2) 'Thus saith the Lord' is awkward Old English. Modern equivalents would include, "God said," "God told me," "God showed me," and "God explained to me." (See 'E' above).
3) It is indeed the nature of humans to reject present prophets while building monuments to past prophets. The End Times differs from this pattern in that all who reject God's prophets will be cut off. They will have no ancestry remaining to build monuments. The monuments to the past prophets will be the living generation, a holy generation, a royal priesthood.