The 23-year-old from Southampton, Pa., outlasted Jacob Hustedt and Lance Rozeboom and Canadians Jonathan Beaulieu-Borgeault and Jaime Peters.
After helping the Charleston Battery win the USL championship last year, Richter had powerful motivation to make it back to MLS in the wake of failing to catch on with the Philadelphia Union and D.C. United.
"You realize how much you want to be back in the MLS," Richter explained after his signing was announced Monday "That was huge for me.
"I realized that when you come here you can't play like you have nothing to lose because you have everything to lose. ... I think that has kind of motivated me more than anything, more than my love of the game or anything like that — some people telling me I can't do it and showing someone that I can."
Manager Ryan Nelsen believes Richter can play across the backline, as well as in midfield.
"Versatile, an extremely good athlete," Nelsen said. "Left- and right-footed. He's a great guy, has a great attitude.
"We just feel in the future he'll be a really valuable guy. He can play a number of positions and I think as he matures and progresses, you never now. I just get a good feeling with him."
Richter himself believes right back is his best spot but says he can play either side in the back and midfield and is willing to play anywhere.
Toronto needs cover at fullback. England's Richard Eckersley will take care of one side but young Canadian international Ashtone Morgan could find himself under pressure from England's Darel Russell and Richter when he returns from Canadian team duty.
Saturday's match against the defending champion Los Angeles Galaxy (2-0-1) is the first of the season at BMO Field. The home opener, a 2-1 win over Sporting Kansas City was played indoors at the Rogers Centre.
Toronto (1-2-0) had a bye last weekend.
Nelsen, for one, is looking forward to his first game at BMO Field after three games on artificial turf in covered stadiums.
"I just can't wait. I think everybody can't wait," he said. "We've been indoors for so long."
Richter and his new teammates worked out at BMO Field for the first time this season Monday, with most donning tuques to shield themselves from a brisk wind on a five-degree day.
Toronto continues to monitor midfielder Julio Cesar, who has yet to see action for Toronto because of a calf strain. The 34-year-old Brazilian took part in some drills Monday then ran with the trainer.
"I think he's very close," said Nelsen.
Attacking midfielder Luis Silva (hamstring) took part in all of practice and should be ready to go.
The Galaxy may be without star striker Robbie Keane. He had to pull out of Ireland's squad ahead of Tuesday's game against Austria after straining his calf in Friday's 0-2 draw in Sweden.
"I said to Darren O'Dea (Toronto FC's Irish international defender) 'Make sure you nail Robbie Keane in training,' Nelsen said. "I was only joking."
"You never know about reports in the media, he could rest up and be fine for the game," the Toronto manager added. "He's a world-class player, isn't he. For me, he was one of the best players in the league last year.
"So if we don't see Robbie Keane in Toronto, I won't be too annoyed about it."
Richter was originally selected in the first round of the 2011 MLS supplemental draft by the Philadelphia Union. That did not work out and Richter landed in Charleston.
"I played a lot and that's huge for a young player, to get this game," he said.
Richter then spent two months with D.C. United but was cut at the last minute. "Kind of heartbreaking but it's a blessing to be here now."
He ended up returning to Charleston for a day. "Drove 12 hours there, then got a call to come here," he said.
Toronto chief scout Pat Onstad, a former assistant coach at D.C. United, brought Richter in. The young defender credits some positive words from Onstad for getting him in the right state of mind.
"I felt confident coming in," Richter said. "I think that's half of it when you're on a trial — showing what you have and not being nervous on the ball."
NOTES — The addition of Richter means Toronto has 28 players on its roster, including injured striker Danny Koevermans. Toronto FC is still working through the paperwork to signing Argentine forward Maximiliano Urruti from Newell's Old Boys.