Software Engineer, Agent Harness

Cursor; New York, San Francisco (NY, CA); On-site; USD 100,000 - 130,000; Full time

Job summary

Cursor is seeking a Software Engineer to join their Agent Harness team in New York. You will develop core agent capabilities that influence user experiences across Cursor products. This role includes advancing agent harness projects and improving the default agent experience.

Ideal candidates have a strong foundation in software engineering, enjoy creating complex products, and have insights into model and agent behaviors. This position offers an opportunity to make significant contributions in the evolving field of coding automation.

Qualifications

• Strong software engineering fundamentals and experience shipping production systems.
• Up-to-date knowledge of emerging research and industry trends.
• Ability to weigh user experience and data in ambiguous situations.

Responsibilities

• Build core agent behavior and capabilities for Cursor products.
• Advance agent harness and improve default agent experience.
• Launch new models based on integration and evaluation.

Skills

Software engineering fundamentals

Building complex agentic products

Model and agent behaviors

Building eval datasets

Job description

Our mission is to automate coding. The first step in our journey is to build the best tool for professional programmers, using a combination of inventive research, design, and engineering. Our organization is very flat, and our team is small and talent dense. We particularly like people who are truth‑seeking, passionate, and creative. We enjoy spirited debate, crazy ideas, and shipping code.

About the Role

As a Software Engineer on the Agent Harness team at Cursor, you’ll build the core agent behavior and capabilities that power agent experiences across Cursor products. This spans agent orchestration, tools, guardrails, and model behavior tuning—designed as a platform that Cursor engineers can extend and depend on.

Your work will also define the default Cursor agent experience (”Auto”), where users trust us to make the right model choices under real-world constraints.

Example projects include:

• Advancing the agent harness (agent loop, tools, prompts, execution environment, capabilities) used across Cursor products. This would shape and empower experiences like multi‑agent coordination.
• Improving the default Cursor agent experience (the “Auto” model setting): making smart model choices based on user needs, model capabilities, and cost appetite.
• Shaping the default Cursor agent’s personality.
• Launching new models on Cursor end‑to‑end — partnering with foundational model providers and our research team on integration, evaluation, and rollout.

You may be a fit if

• You have built complex agentic products or infrastructure.
• You have strong software engineering fundamentals and enjoy shipping production systems.
• You have taste and strong opinions on model and agent behaviors. You stay up-to-date and informed on emerging research and industry trends.
• You make good calls in the gray area: weighing data, user experience, and product taste when there isn’t a single “right” answer.
• Experience building eval datasets or frameworks to understand and improve the performance of AI systems is a plus.
• Experience building products or tools used by other engineers is a plus.