This has been the gold standard for quite some time. The famed Google Guidelines. However it appears that recently Google has moved a specific line item to another area. Placing Rank Checking software users in the same league with websites that install viruses, Doorway pages, and cloakers.
Then to boot threaten action against them via a manual penalty.
Many times you’ll see discussions on reddit or other SEO forums regarding Rank Checking Software. Clearly these do violate Google Guidelines and they are specifically mentioning them in their quality Guidelines and users of them are now given notice that they might get a manual penalty if they decide to take that route.