There is a video circulating since (shortly?) before the Russian invasion of Ukraine (it was published at latest on Feb 15, 2022) in which someone (apparently an "Oleg Pakholkov" (Олег Пахолков) from an outlet called "Блокнот Новости") explains that Russia's sending of troops into Ukraine was completely legal based on the Minsk agreements.1 He reasons that according to the agreements, Russia acts as a guarantor in the agreements and therefore has the right to militarily stop a new local conflict in the troubled regions.
At least in the Wikipedia summaries of the Minsk Agreements, I could not find anything very explicit about this role (but it is well possible I am unaware of certain terms and their implications).
Furthermore, it has been argued that recognizing the Donetsk and Luhansk regions as sovereign was done in part so Russia could legitimately bring troops into those regions, as a support requested by the then recognized local governments. (This point has been discussed, for instance, in a related question.) Which seems unnecessary if they assumed to be legally entitled to move troops into Ukrainian territory, anyway.
For this question, let's keep aside certain factors such as
- sending troops to advance throughout the entire country
- having troops attack plenty of places they come across
- being secretive about the fact that any of your troops are supposed to enter the neighbouring country at all rather than just conducting exercises until right before the attack started
being rather suboptimal solutions to "preventing a local conflict": Is the basic reasoning, that the Minsk Agreements warrant Russia's deploying troops into Ukraine, sound?
1: I hope I did not mix up who said what. Please do point out mistakes in the comments and I'll fix them. I do not speak Russian, and the transcript of the video was a bit confusing about who said what.