Prompt Engineer

MNTN•Austin, TX

3h•Remote

About The Position

At MNTN, we put our people first, full stop. This allows our company culture to be defined by our team members and their shared values, like trust, ambition, quality, radical honesty, and compassionate leadership. It’s why we all really love working for the Hardest Working Software in Television™ (and also why we were named one of Ad Age’s Best Places To Work in 2025.) We pride ourselves on bringing unrivaled performance and simplicity to Connected TV advertising. Our self-serve technology makes running TV ads as easy as search and social, helping brands drive measurable conversions, revenue, site visits, and more. It’s what led MNTN to being named one of Fast Company's Most Innovative Companies in 2023. You can learn more about us and everything we do by visiting https://mountain.com/. We’re committed to innovation that empowers, not replaces. At MNTN, AI is a tool for growth, enhancing efficiency while keeping a people-first approach. Our goal is to streamline workflows and drive new solutions—without compromising the human element that makes our company great. So if wanting to do more, own more, and make a bigger impact comes naturally to you, then you may be the person we're looking for to join us in our next stage of growth. We’re looking for a Prompt Engineer to join MNTN’s engineering team and help define how AI powers our video generation platform. You’ll be hands-on with the prompts and AI workflows that turn structured inputs—brand details, product info, story beats, timing, and creative constraints—into production-ready video outputs. This role is critical to making sure our AI systems are reliable, scalable, and built for real-world use. By owning prompts end to end, setting quality standards, and continuously testing and monitoring performance in production, you’ll have a direct impact on product quality and the trust our customers place in MNTN’s platform.

Requirements

Strong experience with prompt design for large language and generative AI models
Experience testing, validating, and monitoring AI outputs in real systems
Comfort working with structured inputs (schemas, constraints, validation rules)
Systems-oriented mindset with attention to reliability and repeatability
Ability to iterate quickly based on real-world output feedback
Familiarity with multi-model or agent-style AI systems

Nice To Haves

A strong eye for storytelling, pacing, and visual composition
Experience working with video, media, or creative tooling
Experience with Node.js and Typescript

Responsibilities

Design, write, and iterate on prompts for story and script generation, scene and structural descriptions, and dialog, narration, and timing instructions
Build and maintain AI workflows that coordinate LLMs and generative media models while enforcing schemas, rules, and timing constraints
Handle failures, edge cases, and retries across AI-driven systems
Actively test AI outputs to identify failure modes, regressions, and inconsistencies
Define evaluation criteria and lightweight metrics to assess output quality
Monitor production outputs and continuously improve prompts and workflows
Partner with product and engineering teams to translate requirements into durable AI systems
Document prompt patterns, evaluation methods, and workflow behavior