Former Ipswich Town, Peterborough United and Bradford City forward Paul Taylor penned a one-year deal with Rovers following a successful trial period.
Young Liverpool midfielder Herbie Kane, 19, has arrived on loan until January.
And a deal for former Leeds United midfielder Romario Vieira - who McCann sees as one for the future - is expected to be announced today.
“It gives us a bit more strength in depth,” said McCann at his first pre-match press conference of the season.
“In League One you can’t always have too many, if you see what I mean, and we need to make sure we are covered in certain areas.
“Romario is one for the future. He’s one we feel we can develop and he can be a real star here in years to come.
“Tayls is proven in this league. He’s still probably tens days away from full fitness, so whether he’ll be involved at the weekend, we’ll make a decision on that.
“Herbie is a dynamic midfield player who gets about the pitch and breaks things up.”
He added: “Everyone can feel the competition, all over the pitch.
“I’m really pleased with the strength in depth of the squad and I think you need that if you’re going to be successful.”
McCann, whose side start their League One campaign at Southend United tomorrow, has not ruled out any more business before next Thursday’s transfer deadline - but it sounds unlikely.
He said: “It’s done at the minute but in football things change so quickly. People become available.
“We’re always looking.
“We’re not actively looking but if the right person comes along - someone we may have or may not have enquired about - we’ll see if we can do it.
“But I’m really pleased with what we’ve got at the moment.”
Midfielder Ali Crawford (groin) has been passed fit for this weekend after suffering an injury scare in Rovers’ final warm-up game against Sheffield United.