In a message on a Twitter development forum, Twitter development team member Ryan Sarver gave a civil but stern response to third-party developers who wish to build upon the official Twitter client: “Developers ask us if they should build client apps that mimic or reproduce the mainstream Twitter consumer client experience. The answer is no.”

Sarver explained that users are being confused by the various ways they both see tweets and understand the language used to describe twitter functions.

“Still, our user research shows that consumers continue to be confused by the different ways that a fractured landscape of third-party Twitter clients display tweets and let users interact with core Twitter functions. For example, people get confused by websites or clients that display tweets in a way that doesn’t follow our design guidelines, or when services put their own verbs on tweets instead of the ones used on Twitter. Similarly, a number of third-party consumer clients use their own versions of suggested users, trends, and other data streams, confusing users in our network even more.”

The issue, says Sarver, is consistency.  Twitter users need to be able to experience the service in a uniform manner.  He said “some developers display ‘comment’, ‘like’, or other terms with tweets instead of ‘follow, favorite, retweet, reply’ – thus changing the core functions of a tweet,” which implies Twitter is upset with some clients turning their service into something more like Facebook.

Sarver links an updated Terms of Service, which is meant to guide current client app developers.
“If you are an existing developer of client apps, you can continue to serve your user base, but we willbe holding you to high standards to ensure you do not violate users’ privacy, that you provide consistency in the user experience, and that you rigorously adhere to all areas of our Terms of
Service,” he says.

Whether you buy the consistency argument or not, Twitter looks to be serious when it comes to eliminating many third-party clients.

Full text of Sarver’s message here.