Prompt Engineer Jobs in California (NOW HIRING)

Job Summary:
OpenCall.ai is a company focused on enhancing voice AI for multi-location medical groups. They are seeking an AI Prompt & Agent Developer to manage and optimize voice agent behaviors, utilizing data-driven approaches to improve customer interactions and performance metrics.
Responsibilities:
• Write and maintain the prompts that run in production. Intent classification, information extraction, availability negotiation, closing phrases, insurance verification flows, objection handling, edge-case recovery. You own behavior that touches every customer call.
• Ship iteratively against real call data. Every morning, you'll listen to failed calls from yesterday. Every afternoon, you'll deploy a fix. You’ll be using and helping to develop dashboards, call review tooling, and automated agents to accelerate the work.
• Build evaluation harnesses. You'll develop offline eval sets, run automated prompt optimization (we use GEPA-style approaches), and establish the test suites that let us ship changes without breaking live deployments.
• Human-in-the-loop onboarding. New customers come online constantly. You'll work with and iterate on our internal AI agents that translate a practice's intake form, their scheduling rules, and their quirks into an agent configuration. Every week, you'll be designing new evaluation metrics for these customers and helping to improve existing ones.
• QA and continuous improvement. You'll simulate real-world customer scenarios, measure outcomes, and monitor production agent performance so you can catch drift early and fix it fast.
Qualifications:
Required:
• 2+ years of experience with AI/ML, NLP, or prompt engineering in production
• Strong analytical and problem-solving mindset; comfort with ambiguity
• Excellent written and verbal communication skills
• Bachelor's degree and/or extensive experience in one or more of: Computer Science, Engineering, Math, Philosophy, Linguistics, Cognitive Science, English, Medicine, or a related field
• You've shipped prompts that broke production. Doesn't matter if it was at OpenAI, a chatbot startup, a research lab, or your own project. What matters is that you've felt the specific pain of a prompt that worked beautifully in dev and broke the second it hit real users.
• You're meticulous and careful. Looking at data for long stretches energizes you, as long as there's a signal. You stay organized when five things are in flight. We deploy multiple times a day, and we also run healthcare workflows where a bad change costs real money for real practices. You know the difference between moving fast and breaking things.
• Writing sensibility. The best prompt engineers are good writers. You notice register, rhythm, and word choice. You can tell why "Hello, cornerside dental? This is Ava, how can I help you out today? sounds warmer than "Hello, Cornerside Dental, this is Ava. How can I help you out today" out of a TTS.
• Analytical and empirical. You are relentlessly data-driven. Before you make changes, you proactively run experiments and measure. You don't ship because "I think this is better." You justify a change with "this moved booking rate from 78.2% to 81.4% on n=412 calls."
• Comfort with code. You don't need to be a senior engineer, but you should read Python fluently and TypeScript comfortably, and you can get almost any coding task done by pairing with modern AI coding tools.
Preferred:
• Python chops beyond reading: APIs, data pipelines, testing frameworks
• Prior work with voice AI, TTS, ASR, or telephony platforms (Twilio, etc.)
• Contact center, SaaS, or customer-facing tech background
• Healthcare or medical operations experience — you know what an NPI is, you've worked a front desk, you understand the weird chaos of dental scheduling
• Automated prompt optimization experience (DSPy, GEPA, MIPROv2)
• Fine-tuning experience
Company:
Turn missed calls into customers. Even million-dollar call centers lose 10-30% of revenue to abandonment. Founded in 2022, the company is headquartered in San Francisco, USA, with a team of 2-10 employees. The company is currently Early Stage.