Tonks arrived at the capital club in 2012 and has been a mainstay of the side ever since. The 6ft 1in fullback, who can play 10, has appeared 57 times for Edinburgh, running out for his 50th cap against London Welsh away during the pool stages of this year's European Cup campaign, when he kicked a conversion in the win.
Scottish-qualified through his mum, Lena, from Ayrshire, he represented Scotland A in the win over England Saxons in early 2013, ending the season by lifting the Player and Players' Player of the Season awards. He then went on to win his first full cap, against Samoa, in that summer's tour and has now been capped three times, most recently against England last weekend.
Tonks said: "I've been at Edinburgh for three seasons now and I feel as though we have a good group of young guys coming through, keen to play for the club.
"The high points of my time with the club so far have been this season's run in Europe - particularly the away win in Bordeaux - and last season's win over Gloucester. Of course, beating Glasgow to win the 1872 Cup and winning Player's Player of the Year are up there too.
"I'm lucky to be around such a good group of people, there's a good team atmosphere.
"I genuinely believe Edinburgh will be going places in the next few years."
An economics graduate from Leicester University, his new contract sees him stay with the club until at least May 2017.
Scottish Rugby Academy graduate Roddy Grant has played his entire professional career for Edinburgh and will continue to do so for another season, taking him through to May 2016.
A mainstay of the Edinburgh back row since 2009, he was named the league's Young Player of the Season and went on to captain Edinburgh in 2010/11. His 100th appearance for the club came in the 1872 Cup match on Boxing Day 2013 and he recently reached cap number 127, clocking up a phenomenal 103 starts.
Having represented Scotland at under-19 and under-20 levels, he was an early recipient of the John Macphail scholarship (2008) which saw him playing for a summer in New Zealand. He went on to represent Scotland 7s in the IRB World Series that season, in the side's Plate-winning appearance at the 2010 Emirates Airline Edinburgh leg of the tournament and, more recently in the 2014 Glasgow Commonwealth Games.
Grant said: "I've agreed to stay on for a year because I strongly believe in Alan [Solomons] and Stevie [Scott] and going forward with this great group of players at the club."
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