Yeah, 30–40% is pretty high, especially if the other tools are working fine. It definitely sounds like something changed with how Flash-Lite is handling the "end_call" tool after the Retell update. I’ve dealt with similar Retell tool-calling issues before. Feel free to DM me, I can take a look at your setup with you and see if we can get it working reliably without having to switch to a more expensive model.