Senior AI Agent Engineer - Open Models & Evaluation Systems

Sail is the foundation of useful, agentic AI. We are here to take a big swing at the most ambitious engineering challenge of our careers. Everyone working at Sail will become an expert; nothing less will do in our immensely competitive market. Inference is just one piece of an effective background agent. Let's design and build the rest of the system, that turns billions of tokens into the best possible answers. What you’ll do Design custom evals for multi-turn, massively parallel agents. Build agent harnesses to improve open model (Deepseek, Qwen, Llama) performance. Claude Code is all about agent/harness codesign; let's do the same for open source! Automate prompt optimization techniques like DSPy. What we’re looking for Experience building AI agents. Familiarity with open source models. Interview process Meet the CEO. This is the first step because we respect your time. Ask any question and get a definitive answer immediately. Meet the CTO, who will ask about your experience, and share as much technical detail about Sail as you want to hear. Come in to Sail's SF office for an interview day. Meet the whole team, then you'll have 3-4 hours to work on a problem that closely simulates the work we do daily. It's an objectively scored task, so you'll have immediate feedback on how well your code is working - just like we do in production! AI assistance is highly encouraged, and we'll provide a laptop with all the best tools set up. Finish with a short presentation describing your process, learnings, and results. Offer. Once the team decides we want to work with you, we make a strong offer quickly and will be quite persistent over email/text/calls :) Life at Sail We work out of a beautiful, sunny office in downtown San Francisco. All meals are on us (and actually great; SF is a food paradise and it would be a shame to eat only bowl slop). Everyone gets a Studio Display at their desk. We are serious about investing in anything that saves us time or energy. There are six different ways to make coffee or tea in the office. A friendly (hypoallergenic) black cat named Coco visits occasionally. #J-18808-Ljbffr Sail Research