LLM Agent Engineer - Specialist

Mercor; Greater London; On-site; GBP 75,000 - 130,000; Full time

Job summary

Mercor is seeking engineers who build and operate LLM agents in production, with real visibility into how agents are used inside a company. You will discuss how you shipped an agent used by real users, how to tell whether an agent got better or worse after a change, and how to run agents that outlive a single request.

We value experience with long-running tasks, internal data surfaces, and the ability to show what agents did and what they cost.

Qualifications

• Shipped an agent used by real users and owned reliability.
• Can measure if agent performance improves after changes.
• Experience with long-running agents and scheduled jobs.
• Understand internal data access, shared memory, and cost visibility of agents.

Responsibilities

• Design and operate LLM agents in production.
• Evaluate and ensure reliability, adoption, and cost visibility.
• Share practical tradeoffs from real systems.

Skills

Agent deployment

Agent evaluation

Production systems

Adoption tracking

Job description

We are looking for engineers who build and operate LLM agents in production, and who have real visibility into how agents are actually used inside a company.

You have probably:

• Shipped an agent that real users depended on, and been on the hook when it broke.
• Figured out how to tell whether an agent got better or worse after a change.
• Run agents that outlive a single request: scheduled jobs, long-running work, cloud sandboxes.
• Watched your org build an internal assistant, and seen who adopted it and who quietly did not.

We are especially interested in the layers most people do not talk about: internal monoagents wired into company data, shared company memory, reusable skills and playbooks, the tool and MCP surfaces agents call, and how anyone sees what agents did and what they cost.

Applying starts with a short conversational AI interview. No coding, no take-home. We want to hear how you actually think about agent reliability, evaluation, and adoption, and the tradeoffs you have made in real systems. Bring war stories. The messier and more specific, the better.

If that screen stands out, we will invite you to a live 30 minute conversation with our team. We pay $100 to $500 for that conversation, paid on completion of the call, with the amount depending on depth of experience.