An agreement between the two parties, which will see two Scottish Green MSPs enter government and a move towards a shared policy platform, was announced on Friday. Both sides stress that it is not a formal coalition.
The deal will be grounded in co-operation between the two sides in government, Mr Harvie has said. However, opposition parties have deemed it a “coalition of chaos”, and new Liberal Democrat leader Alex Cole-Hamilton has predicted that the Greens will be left “carrying the can” for failures of the Scottish Government.
When asked what stops the Scottish Government from pursuing policy not backed by the Greens, Mr Harvie stated: "Ultimately, if that's the approach they take, then this agreement wouldn't work.
"This agreement is going to be predicated on good faith and depend on the building of trust between both sides.
"That means the Scottish Government is going to have to recognise that they can't put the Greens into impossible positions and it's going to give the Greens the responsibility that what we're arguing for, what we're demanding within government is achievable and deliverable, that we're not asking for the impossible, but we're showing how change can be made possible.
"If both sides work in the spirit of this agreement as well as the letter of it, then it's going to be extremely successful. If either side, the SNP or the Greens, decide that we're going to just demand impossible things from the other side then it will fall apart and the agreement would end at that point.
"I don't think that will happen, I think there is a good degree of trust that has been built up in the process of negotiating this and I think there's a great deal of enthusiasm for making this work."
Some thought has been given to who will take up ministerial office from the Greens and which portfolios they will work within, but Mr Harvie said it could take until the middle of this week for a final decision.
When asked how it felt for him to be standing alongside the First Minister announcing the deal in Bute House on Friday, he said: "The Greens have been working away at our incredibly urgent agenda for many years in opposition and the idea we were about to take the first step into government at this critical time – a week or so after the 'code red for humanity' warning has been issued by the UN, a couple of months before the global climate conference comes to Glasgow – it really does feel like an extraordinary moment of opportunity.
"I expected it to feel a bit like the election debates, those kind of high profile media moments, but it didn't feel like that at all.
"This is really about trying to set a new tone in politics, trying to say political parties can work together when they've got common ground, and still disagree about other issues and conduct those disagreements constructively."