Agencies have been slow to show up in retail media, largely because they were organized around shopper marketing. That is changing. When a holding company hires a senior brand-side retail media leader to build its buy-side practice, it is a sign that real money is coming, along with higher expectations for data, measurement and tooling. As Todd put it, imagine a Paul Revere meme: the agencies are coming.

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Jason O'Toole, EVP and Head of Commerce and Retail Media Activation at Dentsu, joins The Middlemen about two months into the role. Before Dentsu he spent most of his career on the brand side, most recently as head of media and connected commerce at apparel company Gildan, where he ran brand media alongside retail media, DTC, social commerce, agentic commerce, affiliate and digital shelf, stitching those signals together across retailers. He now leads the retail and commerce media practice for Dentsu's network of agencies.

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O'Toole describes a two-part structure at Dentsu. Activation teams are embedded in the individual agencies and own client relationships, while his practice team builds the capability itself, working out how new integrations, like the Amazon and ChatGPT tie-up announced the day before the recording, feed into planning and activation. As retail media growth slows from years of double digits, he sees the pendulum swinging back toward digital shelf and content excellence. Dentsu also runs a separate sell-side practice that helps retailers stand up and manage their networks, the group Brian Monahan came out of before Albertsons Media Collective.

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For retailers learning to work with agencies, his advice is to stay close to the business objective. Top networks ship new products or upgrades almost weekly, and an agency that says no to something is often working within budgets and a tactical plan, not acting as an adversary. Access to data depends on trust: with some clients Dentsu is an activation partner, with others a strategic one, and that trust is what unlocks clean room instances and retail data beyond ads data so the full story can be told.

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O'Toole and Tom co-authored a concept called persona threading. A brand picks three to five personas, runs upper funnel campaigns inside a closed-loop, full-funnel retail or commerce media network, threads those consumers into DSP remarketing, and moves them toward conversion media or product detail pages. He argues the organizations that get there first, across brand, agency and retailer, will hold a real operational and financial advantage. Talent is the constraint: commerce is growing so fast that agencies cannot fill every seat, so they are also retraining seasoned non-commerce staff.

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He calls in-store retail media the industry's lowest-hanging fruit, while acknowledging it is a heavy lift. Cross-category end caps and in-aisle strips could let a brand like Hanes reach grocery shoppers in a way that makes no sense on a grocery website. He also points to the app as the in-store companion, citing an eMarketer figure that about 9% of consumers now use conversational AI tools as their core shopping experience on retailer sites, up from 0% a year earlier. Non-endemic spend is growing faster than endemic, and he expects retailers to compete for that attention with more entertaining and interactive experiences.

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Todd makes the case that agencies exist because of complexity: running a modern campaign touches dozens of technology partners, and retail media is adding its own landscape on top. O'Toole agrees and expects the right agencies to matter more in the next five years than they do today. His next stop is Amazon Unboxed, which may lead to a follow-up dispatch on Shopper Missions.