"Games like this we've really got to turn into three points or we won't get to the play-offs," the 26-year-old told BBC Tees.
"We need to get that nastiness in us, and shut out games."
Despite drawing 2-2 with Newcastle results elsewhere meant Boro closed the gap on the play-off spots by a point.
Austrialia international McDonald, who joined Middlesbrough from Celtic in January, said: "There's 30 points to play for and we've got to get at least half that.
"It's a tough league. Playing against Newcastle you can get up for games like that, it's a big occasion.
"But we have got other games that might not be as big as that but we have to make sure that we have the same attitude as that or we won't be successful."
Source: BBC Sport
Source: BBC Sport