Head of Agent Architecture

At Pencil, we are driving innovation in advertising technology through our state-of-the-art SaaS product, which harnesses Generative AI to redefine content creation. Our mission is to make AI the default in advertising without replacing creative people. To achieve this, we need to make sure that our technology isn’t just in the hands of big brands - we need to try to help small businesses and creative individuals too.

We’re looking for a Head of Agent Architecture: someone who thinks in systems, not just sentences, and who can translate that thinking into a team, a roadmap, and a set of standards the rest of the company builds on. You’ll set the technical vision for agent logic, tool-calling structures, and evaluation loops across Pencil’s core creative engine and our bespoke client work — and you’ll lead a small team of Agent Architects who help you build it.

This is a player-coach role. You’ll spend real time in the architecture yourself, especially on the hardest problems, while also building the team, processes, and standards that let Agent Architecture scale beyond you. You'll also represent Pencil's agent technology directly with brand and agency stakeholders, lead discovery on the most strategic engagements, and set the standard for how your team decomposes client problems and explains complex technical decisions in plain language.

Key responsibilities:

• Strategic Architecture: Define Pencil’s technical vision and roadmap for agent architecture — multi-agent workflows, task decomposition, state management, and tool-use (RAG, API integration, etc.) — and get buy-in from leadership.
• Team Building: Hire, mentor, and manage a small team of Agent Architects. Set the technical bar, give real-time feedback, and run their development conversations.
• Systematic Optimisation: Use and champion evaluation frameworks so agent performance is measured.
• Scalable Frameworks: Own the reusable agents and prompt libraries that let the platform serve 1,000+ brands with unique voices simultaneously, and make the call on what gets built once versus build bespoke.
• Cross-Functional Leadership: Partner with AI Engineering, Product, and Sales/Client leadership to decide what’s handled via prompting, RAG, or fine-tuning.
• Client Architecture: Act as the final technical escalation point for the most complex client deployments. Personally lead discovery on the highest-stakes engagements, decompose ambiguous client problems into buildable agent workflows, and present trade-offs (cost, latency, reliability) to senior non-technical stakeholders. Coach your team to do the same.

Your background:

• 8+ Years of Direct GenAI Experience, with 2+ Years Leading People or a Function: Deep, technical fluency with LLMs (GPT-4, Claude, Gemini) and multimodal models (Stable Diffusion, Midjourney, video gen), plus a track record of managing engineers/architects or owning a function’s roadmap and outcomes.
• Systems Thinking: You think about the latent space, the context window, and how one agent’s output becomes another’s input — and you can teach that thinking to a team.
• Technical Literacy: Comfortable with Python, JSON structures, and API documentation. Experience with agent orchestration patterns (task decomposition, tool use, state management) matters more than any specific framework. You should still be able to get into the weeds when a problem demands it.
• Evaluation Obsession: You believe unmeasured prompts shouldn’t ship, and you’ve built or run benchmarking/A-B testing practices — not just used them.
• Leadership & Influence: You’ve hired and grown technical people before, or you’ve owned a roadmap with real stakeholder pressure. You can set a strategic vision, get it approved by senior leadership, and hold a team accountable to it.
• Client-Facing Problem Decomposition: Demonstrated experience leading discovery with senior customers or stakeholders and turning vague briefs into scoped technical solutions. Solutions architecture leadership, forward-deployed engineering, or technical consulting backgrounds fit well here.
• Plain-Language Communication: You can explain agent failure modes, eval results, and architectural trade-offs to a CMO without jargon — and you hold your team to the same standard.
• The "Creative/Technical" Bridge: You can sit in a room with a Creative Director and translate "make it feel more punchy" into a concrete change to the system — and you can teach your team to do the same. You are comfortable being the face of the technology in client meetings, not just the person behind it.

You’ll Thrive Here If You…

• You find “hallucinations” a logic puzzle to solve, not just a bug — and you like teaching others to solve them too.
• You'd rather sit with a confused client and untangle their problem than receive a perfect spec — and you hire people who feel the same.
• You’re excited by the challenge of making an AI follow a 50-page brand book with 100% fidelity, and by building the team and standards that make that repeatable.
• You want to build the infrastructure — and the people — that define how the next generation of advertising is created.

KPIs & Success Measures

• System Reliability: Reducing the failure rate of complex agent workflows across the platform.
• Architectural Efficiency: Minimizing token usage/latency while increasing output quality.
• Brand Alignment: Automated-evaluation scores of agent output against brand guidelines.
• Adoption at Scale: Core agents adopted and retained across the Pencil user base, not just shipped to it.
• Client Deployment Success: Custom client workflows delivered on time and adopted by the client, measured from brief to live, not build complete.
• Stakeholder Trust: Clients and internal partners come back to your team to scope the next problem. Repeat engagement on strategic accounts and positive feedback on clarity of communication.
• Team Growth: Hiring, retention, and development of the Agent Architecture team, including their ability to run client engagements without you in the room.

Benefits:

• 25 days PTO plus public holidays, although we operate a Flexible Time Off scheme
• Health insurance / private medical cover
• Monthly stipend towards wellness, fitness, and learning and development
• Remote - work from anywhere in your home country
• Enhanced parental leave policies, whether you become a parent through birth, adoption or surrogacy
• Access to our Pencil office in The Shard, London for UK employees
• Flexible working hours

Deep Dive About Pencil

Pencil uses AI to make ads. Our mission is to make marketing effective and effortless. We want to become the default way ads get made - because AI ads are 10x faster and cheaper to make, and 2x better performing, than making them without AI.

We’re called Pencil because we believe AI will be a tool for creative people, not a replacement - it may even be as fundamental a tool in the future as the pencil was in the past.

Pencil was founded in 2018 with a team from Google, Facebook and Uber with backing from Sequoia and Entrepreneur First. We were acquired by The Brandtech Group in 2023 to pursue a shared vision of bringing GenAI to the Fortune 500.

About The Brandtech Group

The Brandtech Group’s mission is to be the best company in the world at helping leading global brands drive growth by connecting content, data and media using technology.

It was founded in June 2015 (as You & Mr Jones) by former Havas Global CEO David Jones, with a simple mission to help brands do their marketing better, faster and cheaper using technology. It was renamed The Brandtech Group in January 2022.

Today it generates more than $1BN in revenue and is the largest global digital content partner for many of the world's biggest brands and companies, often using its unique in-housing model. It works with eight of the world's top 10 global advertisers and 49 of the world's top 100. Clients include Banco Itaú, Danone, Google, Intuit, LVMH, Microsoft, Morgan-Stanley, Netflix, Reckitt, Renault-Nissan, PayPal, TikTok, Uber and Unilever.

In addition, the Group invests in cutting-edge technology companies relevant to and with potential in marketing and has been investing in the AI, AR and the metaverse space since 2015. The Group was the first external investor in Niantic (creators of Pokémon Go), alongside investments in AI Foundation (AI digital twins, personalized AI, and deep-fake detection 2018), Automat (AI chatbots, 2016), Elsy (AI media planning, 2016), Jivox (dynamic automated content,, 2016), Crossing Minds (deep learning AI recommendation system, 2017), CreativeX (AI-driven content optimization, 2022), Zappar (AR, 2017), Provenance (blockchain, 2022) and GGP (the world's largest gaming fund).

The Group is one of the most prominent marketing industry voices on the prediction and movement to AI-driven marketing, including Generative AI. It was named one of the World's Most Innovative Companies 2021 by Fast Company, and by CB Insights as one of the World's Most Valuable Private Unicorns.