Everyone knows the amazing positional ability and endgame ability of Magnus Carlsen, but how is his tactical skills. I have heard someone say tactics are not his specialty? is this accurate
You can't be a strong positional player without being a strong tactical player... and you can't be a strong tactical player without being a strong positional player. The two go hand in hand, and when a player is strong they tend to be strong in both domains. Here's one way of explaining this. In order to achieve a good position, you have to see the tactical possibilities on the board. This will let you find good squares for your pieces and activate them. And in order to have tactical possibilities, you need to achieve a good position, as tactics flow from a good position. That's why the two are connected. For someone of Magnus's strength (the best in the world) you have to be extremely strong in both. So, to answer your question, he is extremely strong at tactical chess, positional chess, and endgames.
Another question you might ask is, what is his style? Does he play tactically or positionally? A player's style is largely composed of the positions they have learned and the openings they choose. Historically Magnus has a positional style as he tends to play strategic positions over sharp, tactical ones. However, recently this has changed. In the World Championship against Caruana, he played one of the sharpest openings with black, the Sicilian Sveshnikov. In Tata Steel he reprised this opening. Thus it seems that he is favoring sharp openings with black these days, perhaps out of his desire to win more games and play fewer draws. It will be interesting to see how he plays during the rest of the year. Will he continue to play sharp, unbalanced openings with black? Will he continue to play aggressively with considerable risk? To draw a connection between this question and the one you asked, it's important to point out that Magnus can do this -- switch from a positional style to a sharper and more aggressive style -- because he is so strong both tactically and positionally.
Here is a masterful endgame he played in 2012 which showcases both strategy and tactics. Notice how 38. Kd5 involves a tactic that lets him improve his position, an example of how tactical and positional chess are connected. Another example would be 49. f6.
[fen ""] [Event "Grand Slam Chess Final"] [Site "Sao Paulo BRA"] [Date "2012.10.08"] [EventDate "2012.09.24"] [Round "6"] [Result "1-0"] [White "Magnus Carlsen"] [Black "Fabiano Caruana"] [ECO "C00"] 1.e4 e6 2.d3 d5 3.Nd2 Nf6 4.Ngf3 Nc6 5.c3 Bd6 6.Be2 O-O 7.O-O a5 8.Re1 e5 9.exd5 Nxd5 10.Nc4 Re8 11.Bf1 Bg4 12.h3 Bh5 13.g3 Nb6 14.Nxb6 cxb6 15.Bg2 b5 16.a4 b4 17.Be3 Bc7 18.Qb3 h6 19.Qc4 bxc3 20.bxc3 e4 21.dxe4 Bxf3 22.Bxf3 Ne5 23.Qe2 Nxf3+ 24.Qxf3 Qd3 25.Kg2 Qxe4 26.Bd4 Qxf3+ 27.Kxf3 b6 28.Rab1 Rac8 29.Re4 g6 30.g4 Kf8 31.h4 Rxe4 32.Kxe4 Re8+ 33.Kd3 Re6 34.Be3 Kg7 35.Rb5 Bd8 36.h5 Rd6+ 37.Kc4 Rc6+ 38.Kd5 Re6 39.Bd4+ Kf8 40.f4 Bc7 41.f5 Rd6+ 42.Ke4 Rc6 43.Rb1 Ke8 44.hxg6 fxg6 45.Rh1 Kf7 46.Kd5 Rd6+ 47.Kc4 gxf5 48.gxf5 Bd8 49.f6 Bxf6 50.Rxh6 Be7 51.Rxd6 Bxd6 52.Kb5 Ke6 53.Bxb6 Kd7 54.c4 Kc8 55.Bxa5 Kb7 56.Bb4 Bf4 57.c5 Ka7 58.c6 Kb8 59.a5 Ka7 60.a6 Ka8 61.Bc5 Bb8 62.Kc4 Bc7 63.Kd5 Bd8 64.Ke6 Bc7 65.Kd7 Ba5 66.Be7 1-0
Here's a Sicilian he played as white against Karjakin in the 2016 tie break. He plays a strategic Maroczy bind in the opening but uses a clever tactic to win at the end.
[fen ""] [Event "Carlsen - Karjakin World Championship Match"] [Site "New York, NY USA"] [Date "2016.11.30"] [EventDate "2016.11.11"] [Round "13.4"] [Result "1-0"] [White "Magnus Carlsen"] [Black "Sergey Karjakin"] [ECO "B54"] 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.f3 e5 6.Nb3 Be7 7.c4 a5 8.Be3 a4 9.Nc1 O-O 10.Nc3 Qa5 11.Qd2 Na6 12.Be2 Nc5 13.O-O Bd7 14.Rb1 Rfc8 15.b4 axb3 16.axb3 Qd8 17.Nd3 Ne6 18.Nb4 Bc6 19.Rfd1 h5 20.Bf1 h4 21.Qf2 Nd7 22.g3 Ra3 23.Bh3 Rca8 24.Nc2 R3a6 25.Nb4 Ra5 26.Nc2 b6 27.Rd2 Qc7 28.Rbd1 Bf8 29.gxh4 Nf4 30.Bxf4 exf4 31.Bxd7 Qxd7 32.Nb4 Ra3 33.Nxc6 Qxc6 34.Nb5 Rxb3 35.Nd4 Qxc4 36.Nxb3 Qxb3 37.Qe2 Be7 38.Kg2 Qe6 39.h5 Ra3 40.Rd3 Ra2 41.R3d2 Ra3 42.Rd3 Ra7 43.Rd5 Rc7 44.Qd2 Qf6 45.Rf5 Qh4 46.Rc1 Ra7 47.Qxf4 Ra2+ 48.Kh1 Qf2 49.Rc8+ Kh7 50.Qh6+ 1-0
And here's a blitz game he played in 2015. A lot of these moves, including the tactical blows at the end, he played almost instantly. Notice how 19... Bf5 20. Qd2 would lose to 20... Be4 with an unstoppable mate. In a blitz game it's very hard to respond to a move like 19... Bf5. Everything goes downhill after 20. e4 Qxd3. And 24... Bb4 followed by 25... Bd3 is a clever way of saving material after 24. Rd2 put both bishops in a skewer.
[fen ""] [Event "banter blitz"] [Site "chess24.com"] [Date "2015.11.??"] [EventDate "2017.??.??"] [Round "?"] [Result "0-1"] [White "Jan Gustafsson"] [Black "Magnus Carlsen"] [ECO "A96"] 1.Nf3 f5 2.g3 Nf6 3.Bg2 e6 4.O-O Be7 5.c4 O-O 6.Nc3 d6 7.d4 a5 8.b3 Qe8 9.Ba3 Na6 10.Rc1 Nb4 11.Qd2 Ne4 12.Nxe4 fxe4 13.Ne1 Qg6 14.Nc2 Bg5 15.e3 Nd3 16.Rcd1 e5 17.Bxe4 Qxe4 18.Qxd3 Qf3 19.dxe5 Bf5 20.e4 Qxd3 21.Rxd3 Bxe4 22.Rc3 Bd2 23.Re3 Bxc2 24.Re2 Bb4 25.Bxb4 Bd3 0-1
He's definitely one of the most tactically skilled players on the planet. Arguably not the #1 tactical player, but he's definitely up there in the highest echelon.
He's more known for his endgame abilities, but that doesn't mean that he's lacking tactically. He wouldn't be able to gain and retain the world championship title for 6 years if he was.