Philip：So, you're an exchange student. Where do you go to school?
Alexandra：At the Bronx High School of Science.
Philip：Oh, that's a very good school. What are your favorite subjects?
Alexandra：Biology and mathematics. Richard tells me you're a doctor.
Philip：Yes, a pediatrician.
Richard has told Alexandra that Philip is a doctor before this dialogue happens. I would say Richard has told me you're a doctor instead of tells me.
Is it all right to use present simple here? Why?
It is a kind of historic present, and one which is fairly common in conversation when referring to what another person has said.
I was talking to my dad, and he says that you are looking for a gardener.
Well, my wife claims to have seen a UFO.
Martin tells me that you are getting married.
The implication in using the present tense is that "If I were to ask again, he would say the same thing."
For example if I said "My wife claimed to have seen a UFO" it would imply that she has now changed her mind and does not claim this anymore.
Somehow saying "Richard tells me that you're a doctor", invites the other person to respond. Whereas "Richard told me that you're a doctor" doesn't. The second is just a statement of fact. The first is a invite for the person to speak more about being a doctor.
It is OK to use the simple present with tells in this locution because native speakers have been saying it for some 400 years. It might be paraphrased "I am told by Richard that ..." or "I understand from speaking with Richard that ..."
The form emphasizes the fact that the speaker is one of Richard's acquaintances, that they have met and are on speaking terms, and that what has been told was told quite recently, so recently that the speaker believes the fact is still "fresh".
One could even use this form at a cocktail party or reception or other occasion that involves chit-chat, after being introduced to someone who tells you about themselves and a little about their spouse or significant other, for example. When that person later joins the conversation you might say:
Richard tells me you're a doctor.
But it doesn't have to be that recent:
The curator tells me the brooch I found when digging in my garden is from the 8th century.
The conversation being referred to might have taken place a year ago or more.
Time-wise it is similar to:
I have had this pain in my knee ever since I stepped into that pothole near the curb in the Main Street crosswalk and wrenched it.
--Really? That was over a year ago. What do the doctors say?
What is the opinion of the doctors? Presumably they have been consulted in this matter, and presumably their opinion has not changed.
The simple present tense indicates a habitual occurrence, and indicates no definite point in time. If one were to say, "He is not a vegetarian, so he eats meat," this does not state that the person ate meat a single time, but implies that the person is willing to eat meat, and possibly has done so many times.
Your example:
Richard tells me you're a doctor.
This suggests that Richard is willing to share that fact, and doesn't limit the number of times he has shared it. It indicates that the information is current (Richard hasn't taken the statement back), and therefore invites Philip to add to the statement.
