You must authorise with Flickr to be able to add tags to Flickr and make suggestions.
Click on the Login button below and you will be asked to authorise the app using your Flickr login (requires Flickr/Yahoo account). Full permission is required in order to use the service to add tags and comments, and also for in the case of Flickr Commons image owners to be able to review user suggestions (e.g. dates and locations) and update image metadata directly on Flickr based on these suggestions.