Member of Technical Staff- Research Engineer (Harness Engineering and Agentic Orchestration)

The role

You will work on the AI Research team to develop components for agent harnesses, orchestration, evaluation methodologies, and failure-mode analysis. You will collaborate with engineering, product, and design to build and improve AI-powered software development infrastructure.

What you will do

• Design evals to capture how customer agents are failing
• Close the outer loop from production signal to harness changes
• Own slices of eval infrastructure including dataset curation and runner
• Prototype new harnesses or context configurations
• Build tooling to analyze agent traces
• Partner with product and engineering on shipping problems
• Turn research papers into concrete experiments

Required qualifications

• 4+ years shipping AI/ML products in a startup or applied industry setting
• Recent hands-on experience with LLMs and agentic systems
• Demonstrated depth in at least one of the four skill areas: Agent harness and orchestration design, Agentic eval methodology, Outer-loop and pipeline thinking, or Failure-mode analysis
• Strong product and customer instincts
• Sharp evaluation judgement
• Experience building datasets for evaluation or training

Nice to have

• A Masters or PhD in a relevant computational field
• Direct experience with coding agents or code-generation systems
• Background in RL, bandits, or other outer-loop optimisation frameworks applied to LLMs
• Experience building synthetic data, dataset infrastructure, or internal tooling
• A project you can show us (GitHub links welcome)

Benefits

• Market-benchmarked salaries and EMI share options
• 25 days of annual leave
• UK public holidays
• Two paid volunteering days each year
• Vitality medical insurance including dental, optical and mental health support
• 5% employer pension matched contribution through Smart Pension
• Company-paid life insurance of four times your annual salary
• Enhanced Maternity, Parental and Adoption Leave from day one
• £1,000 per year for learning and development
• Financial support for eligible team members commuting from outside Greater London
• Cycle to Work scheme
• Twice a year week-long offsites

Before you apply

• Intro call to understand Why Tessl?
• Call with AI Research Lead
• 4 hour technical take-home exercise
• Half-day on-site session including whiteboarding and hands-on activities
• Leadership chats with Head of People, Head of Engineering and CEO

About the company

Tessl is a fast-growing Series A startup building infrastructure for AI-powered software factories. It was founded by Guy Podjarny, previously founder of Snyk.