Paceman Shaun Tait also claimed three victims, taking advantage of a track which gave plenty of encouragement to the fast bowlers.
"There was a lot more bounce in this wicket than we have had in the other places around the West Indies," said man-of-the-match McGrath.
"I felt the wicket was pretty good, good bounce, good carry early on. There were a few that kept a bit low so hopefully for the final it will be a bit more consistent," he said.
McGrath, who will retire from cricket at the end of the World Cup, said he was particularly pleased to see a lively track at one of pace bowling's traditional homes.
"I look back mainly at the test matches. In 1995 the wicket here was good carry, good pace and good bounce. 1999 was still okay but 2003 was one of the slowest wickets I have ever played on.
"To come back here and have the pace and bounce back in the wicket is great and I'm looking forward to be being back here for the final.
"To me that is what the West Indies is about -- I grew up watching in the mid-eighties with four fast bowlers steaming in and pace and bounce so it is good to have a wicket like that here."
The Australian, now the tournament's top wicket-taker with 18, said that Ireland should not be too downhearted about their loss.
"When we play well there are not too many teams in the world that can beat us and Ireland probably aren't up to the standard of other teams so it was always going to be tough for them."
