Founding Harness Engineer – AI Agents

This is a fully remote position, open to applicants in Argentina, +4 more countries.

📋 Description

• Develop the agent runtime, focusing on context management, tool selection, approval waits, and determining when to take action, inquire, or remain silent.

• Craft and continuously refine the system prompts, ensuring proactive engagement without overwhelming the team channel.

• Take ownership of the evaluation and regression framework; treat prompt modifications with the same rigor as code testing.

• Ensure that long-duration tasks can withstand interruptions, retries, and unreliable APIs.

• Establish guardrails, including approval checkpoints for high-risk actions and stringent separation of customer data.

• Collaborate closely with the founder and early adopters, transforming their feedback into implemented functionalities.

⛳️ Requirements

• You have successfully deployed tool-using LLM agents to real users in a production environment; demos and prompt wrappers are not considered sufficient.

• Strong instincts regarding agent initiative, supported by relevant test outcomes.

• Practical experience in constructing evaluation and regression suites to assess LLM behavior.

• A solid understanding of safe tool execution, prompt injection, and the risks associated with multi-tenant data.

• Proficient backend development skills in Python or TypeScript, including experience with asynchronous jobs, retries, and state management.

• Ability to navigate a vague problem from prototype to production, articulating the trade-offs encountered throughout the process.

• Exceptional written and verbal communication skills; capable of explaining trade-offs to a founder or a user without the aid of a whiteboard.

• Nice to have: Experience with MCP or integrations with platforms such as Slack, Gmail, Notion, or Linear.

• Nice to have: Familiarity with evaluation and tracing tools like Braintrust, Langfuse, or LangSmith.

• Nice to have: Previous experience as an early engineer at a startup and a positive attitude towards that experience.

🏝️ Benefits

• Founding equity.

• Direct access to the founder and early users, with no intermediary layers.

• Remote work opportunities available from Latin America or Eastern Europe, ensuring substantial overlap with US Pacific time.

• Access to the tools and models necessary to perform your job effectively.

• Join a small, experienced team that empowers you to manage your own projects.