The Jags are preparing to launch their push for promotion – McNamara has made it clear there is no point in aiming for anything other than that – and having been a key part of St Mirren's midfield, Murray has plenty to bring to the table.
The 33-year-old had a disappointing final term with the Paisley side when he recovered from injury only to struggle to sustain a starting place under Danny Lennon.
And after kicking his heels, he is eager to get back to action at Firhill.
"The physio said to me last year that the time I had to spend out of the game because of the knee injury should help me prolong my career," he said. "I'm just looking forward to the new challenge.
"It is something fresh and I'm desperate to get stuck in. I know Jackie well. We overlapped as players and came up against one another.
"Hopefully I can repay his faith in me by going out and trying to help us move on a little bit this term."
Murray played the opening half of Tuesday night's friendly against Alloa and after working hard on his own throughout the close season, he strolled through the encounter.
"It is nice to get a good pre-season," he said.
"I wasn't back until November last season so it just feels good to be getting back into it.
"Any player will tell you how important it is to get a good pre-season under your belt – it really sets you up for the season.
"I am desperate to get going. Once the season gets underway properly the games start to come thick and fast and I believe that I still capable of that kind of pace. I'm excited by the challenge."