In a move that Google says was designed to “ensure quality, improve Google products and services and compliance with AdWords API Terms and Conditions,” the company earlier this week revoked access to the AdWords API to a large number of developers, raising the ire of many who complained about a lack of warning and communication, along with damage to their businesses and clients.

The reverberations of the apparent attempted clean-up has been significant, with nearly a hundred AdWords API developers reporting in a discussion group that their developer token had been suddenly revoked — though some had previously had access to the API for months, or even years — with no notice from Google.

“The Google API is a critical piece to many publishers – large and small – who make informative decisions based upon the investment they make in the AdWords program,” Jason Prescott , CEO of TopTenWholesale.com and Manufacturer.com, told me in an e-mail exchange. “Our marketing teams, customers, and numerous resources all become accustomed to a certain way of managing aspects of their daily duties. When a wrench is thrown, the rattling caused equated to losses that are not only quantifiable – but at times crippling.”

Originally, the problem was suspected to be a bug, but, later, Google confirmed that the action was a result of a periodic review of API activity, a spokesperson said.

To have their developer token reactivated, API developers must re-apply and include specific detailed information:

The uses of the API application or tool with specific examples. Is it for bid optimization or account management?

Who will using the API application or tool? People within your company or others to whom the application will be sold?

Google is also asking for screenshots of the API app or tool, or design documentation if the product is in development. Additionally, it wants a list of clients that will be using the API application or tool “in an automated way.”

So far, at least one API developer — Jason Prescott of TopTenWholesale.com and Manufacturer.com, who I quoted above — has been granted “provisional” access to the API again, after writing an e-mail and contacting a Google representative. Prescott’s company will have to provide all of the above information before September 23, and presumably it will have to meet Google’s requirements, before the access decision becomes final.