Founding AI Harness Engineer — SF, Onsite, Equity

Heyjared; San Francisco (CA); On-site; USD 250,000 - 350,000; Full time

Benefits offered by this job

Equity

Job summary

Heyjared in San Francisco invites a founding Harness Engineer to build an agent runtime that acts as a proactive yet prudent teammate. You’ll design prompts, implement tool use, and ensure safe, multi-tenant data practices as you collaborate with the founder and early users.

You will ship production-grade agents, craft robust evaluation harnesses, and drive prototypes to production, with equity and a high-impact founding role in a hands-on, in-person setting.

Qualifications

• Shipped agents that use tools in production, not demos or prompt wrappers.
• Hands-on system prompt design improved through testing.
• Strong experience with regression/eval harnesses.
• Knowledge of safe tool execution and data risk management.

Responsibilities

• Design and build the agent runtime: how Jared gets context, decides when to speak, chooses tools, waits for approval, completes work.
• Write and iterate system prompts: proactive without noisy or reckless.
• Build eval and regression tests around real tasks, tool use, failure cases.
• Make behavior reliable across long-running work, interruptions, retries.
• Build safe boundaries: approval gates, multi-tenant data separation.
• Work directly with the founder and early users.

Skills

Agent orchestration

System prompts

Regression harness

Tool integration

Security boundaries

Job description

Heyjared in San Francisco invites a founding Harness Engineer to build an agent runtime that acts as a proactive yet prudent teammate. You’ll design prompts, implement tool use, and ensure safe, multi-tenant data practices as you collaborate with the founder and early users.

You will ship production-grade agents, craft robust evaluation harnesses, and drive prototypes to production, with equity and a high-impact founding role in a hands-on, in-person setting.