Senior AI Agent Engineer

Senior AI Agent Engineer – $90k-$190k (depending on location)- Remote, Europe

Plexus is partnering with a fast-growing generative AI company to hire a Senior AI Agent Engineer. The business is building AI-powered tools that help companies create consistent, brand-aligned marketing and creative content at scale, supporting both self-serve users and global enterprise customers.

You’ll join a small, high-autonomy engineering team building the shared AI infrastructure behind the platform, with a focus on production-ready agent systems, enterprise workflows, reliability, cost, and performance.

Role Overview

As Senior AI Agent Engineer, you’ll design and ship modular agentic systems that can be used across internal tools, customer-facing products, and customised enterprise deployments.

This is not an ML research role. You’ll work one layer above the model, turning LLM prototypes into reliable systems used by real customers.

Core Responsibilities

• Design and build reusable AI agents, tools, and workflow infrastructure.

• Develop agent loops covering planning, tool use, retries, and reflection.

• Build retrieval, context, and memory systems using RAG approaches.

• Create evaluation frameworks, regression tests, and performance benchmarks.

• Improve latency and cost through caching, model routing, and optimisation.

• Build integrations, connectors, tool wrappers, and permission layers.

• Take AI features from prototype through to production.

• Work directly with enterprise customers to understand technical requirements.

• Contribute across the backend and frontend where required.

Requirements

• Production experience building LLM-powered or agent-based products.

• Strong experience across agent architecture, tool use, RAG, evaluation, memory, or context engineering.

• Strong TypeScript skills and working knowledge of Python.

• Experience with frameworks such as LangGraph, CrewAI, AutoGen, or similar.

• Strong software engineering fundamentals, including APIs, testing, concurrency, and production debugging.

• Full-stack capability across backend and frontend systems.

• Experience working directly with clients or external stakeholders.

• Comfortable operating autonomously in a fast-moving environment.

• Based in Europe and able to work across European time zones.

Nice to Haves

• Experience building multi-agent or long-running agent systems.

• Knowledge of MCP servers, sandboxed environments, or agent observability.

• Experience with model routing, prompt caching, or evaluation tooling.

• Background in generative media, marketing technology, or content platforms.

• Open-source contributions to AI agent frameworks or tooling.

• Experience across both startup and larger-company environments.

Perks & Benefits

• Fully remote with flexible working patterns.

• Uncapped, manager-approved learning budget.

• Annual health and wellbeing allowance.

• Optional team travel.

• High ownership within a small, experienced engineering team