A common way to handle grant applications seems to be to request external reviews, to which the applicant can then respond. Reviews and response together are discussed at a panel where the proposals are ranked, and the top x% then are funded.
I've found myself in a nice, but perplexing situation: I got back the reviews for my first grant proposal, and all reviewers gave top scores (and very positive comments). Now I'm wondering whether or not to use my right to respond - all information I could find about responses boil down to addressing criticism, but what do you do if there is no criticism?
Edit: The grant agency explicitly discourages using the reply to thank reviewers. The alternative option besides not replying at all could be to attempt to selectively agree with the most praising comments or something like that, but I'm not sure that is a good idea.