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

TesslLondon OfficeR&D
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Salary
Not listed
Job type
Full-time
Work mode
Remote
Posted
28 May 2026
Status
Open · checked 7d ago

About this role

Role Overview

Tessl is seeking a Member of Technical Staff - Research Engineer specializing in Harness Engineering and Agentic Orchestration for their R&D team. This hybrid position is based out of the London office or available remotely, offering early team members a chance to shape the future of AI-native software development. The ideal candidate will combine deep technical expertise in AI systems with a strong customer-centric mindset to build robust agent harnesses and evaluation pipelines.

Key Responsibilities

Participate in customer sessions to understand agent failure points, design targeted evaluations, and drive fixes to production.
Manage end-to-end outer-loop processes, moving from production signals and datasets to scored evaluations and shipped harness changes.
Own segments of the evaluation infrastructure, including dataset curation, harness configuration, runners, and result analysis.
Prototype new harness or context configurations to measure performance impacts on real customer tasks.
Analyze agent traces, develop necessary tooling for data interpretation, and brief the team on findings.
Collaborate with product and engineering teams by applying rigorous research methodologies to near-term shipping challenges.
Analyze recent research papers, assess transferability to the platform, and execute concrete experiments.

Requirements

At least 4 years of experience shipping AI/ML products within a startup or applied industry setting, featuring recent hands-on work with LLMs and agentic systems.
Demonstrated depth in at least one of four core areas: agent harness and orchestration design, agentic evaluation methodology, outer-loop and pipeline thinking, or failure-mode analysis.
Strong product and customer instincts, including comfort joining customer sessions, reviewing recordings, and letting real workflows guide research priorities.
Sharp evaluation judgment utilizing standard benchmarks or quick prototypes where appropriate.
Practical experience building datasets for training or evaluation, alongside the supporting pipeline work.
Genuine curiosity about AI agents and enthusiasm for reshaping modern software development.

Nice to Have

A Master's or PhD in a relevant computational field.
Direct experience working with coding agents or code-generation systems.
Background in reinforcement learning, bandits, or other outer-loop optimization frameworks applied to LLMs.
Experience building synthetic data, dataset infrastructure, or internal tooling for engineering teams.
A shareable project or GitHub link along with a thoughtful answer regarding motivation for joining the company.

Skills and Tools

Large Language Models (LLMs)
Agentic Systems and Harness Design
Agentic Evaluation Methodologies
Outer-Loop and Pipeline Optimization
Failure-Mode Analysis and Trace Instrumentation
Dataset Curation and Pipeline Building

Salary and Benefits

Competitive salary matching candidate experience levels.
Comprehensive health insurance covering partners and dependents.
Pension contributions.
Pet-friendly London office located near King's Cross featuring regular team lunches, drinks, and socials.
Hybrid work model with primary in-office days on Monday, Tuesday, and Thursday.

About the Company

Tessl is a fast-growing Series A startup headquartered in London, founded by serial entrepreneur Guy Podjarny. Backed by over $100 million from top-tier investors like Index Ventures, Accel, GV, and Boldstart, the company is building the context layer for AI coding agents and a platform for AI-native software development. Recognized widely in the industry, Tessl values an inclusive, warm environment and encourages applicants from all backgrounds.

How to Apply

Candidates interested in joining the Tessl team should apply directly on the official company careers page.

Questions candidates ask

Where is this job located?

This role is based out of the London office, located a couple of minutes from King's Cross, with remote flexibility. The team operates on a hybrid schedule with primary in-office days on Monday, Tuesday, and Thursday.

What experience is required for the Research Engineer role?

Candidates must have 4+ years of experience shipping AI/ML products in a startup or applied industry setting, with recent hands-on experience involving LLMs and agentic systems.

What specific skill areas are important for this position?

The team looks for depth in at least one of four areas: agent harness and orchestration design, agentic evaluation methodology, outer-loop and pipeline thinking, or failure-mode analysis.

What does the application process involve?

The process includes an introductory call, a conversation with the AI Research Lead, a 4-hour technical take-home exercise, a half-day on-site session with whiteboarding and hands-on tasks, and final leadership chats.

What benefits are provided with the job?

Benefits include a competitive salary, health insurance extending to partners and dependents, pension contributions, and a pet-friendly office environment with team socials and lunches.

Ready to apply?

The application is on the official Tessl careers page.

Apply on company site