What Does Agent-to-Agent Media Buying Mean for Publishers?

Every major publisher knows this feeling: you have assets that are worth more than the market is currently paying for them. A deeply engaged audience. First-party data built over years. Premium editorial environments that brands genuinely want to be part of.

The demand for what you have is real. The challenge has always been connecting it consistently to the buyers best positioned to utilize it, at a pace and scale that works for both sides.

Agent-to-agent media buying is the first mechanism that addresses this directly. It creates a direct, unmediated path between buyer intent and publisher inventory — one where publishers can fully deploy what they’ve built on every transaction.

In previous pieces, we’ve explored why agent-to-agent buying matters and how AdCP enables it. Here, we focus on what this shift looks like from the publisher side: how inventory gets discovered and evaluated in agent-driven workflows, and what it takes to participate.

What you’ll learn:

• Why agentic buying lets publishers unlock the full value of their audiences and content in every transaction
• What it means to be discoverable by agents, and why it opens new commercial possibilities
• How agents evaluate and select inventory in real time — and what determines whether yours gets chosen
• What publisher participation requires technically and commercially, and how to get started
• Why publishers entering the market now are building an advantage that compounds over time

Publishers have always had the value. Agentic advertising unlocks it at scale.

Publishers have built valuable assets, including rich first-party audience intelligence, premium inventory across high-quality editorial environments, and contextual depth that drives real brand outcomes. But the challenge has never been the value itself. It’s been delivering it consistently, across the full range of campaigns that could benefit.

A direct deal captures the full depth of what a publisher offers, but requires onerous human coordination on both sides that limits scalability. Auction-based channels extend reach but weren’t designed to carry the kind of contextual and audience depth that makes a publisher’s inventory distinctive. Many campaigns that would perform exceptionally well against a publisher’s best assets simply have no efficient path to them.

Agent-to-agent buying changes the equation. When a buyer’s agent engages directly with a publisher’s sales agent, the transaction happens within the publisher’s own environment, with embedded human oversight for strategic judgment. The full depth of a publisher’s first-party intelligence can be applied with the precision sellers have always been capable of, now extended to campaigns and deal sizes that previously couldn’t justify the process.

Our CEO Brian O’Kelley recently framed it succinctly to a room full of publishers: the opportunity in agentic advertising is to sell beyond the impression — exclusivity, bundles, and scarce access to specific audiences in ways that reflect their actual value. “You’ve got that opportunity,” he said, “and I think it’s valuable.”

From biddable to discoverable: a new way publishers compete and win

Programmatic created scale and access, which gave publishers a reliable monetization channel and connected them to demand they couldn’t have reached through direct sales alone.

Agentic advertising is something new in its own right. A brand’s AI agent interprets a campaign brief and reaches out directly to publisher-side sales agents — expressing intent, querying inventory, and evaluating what’s available based on how well it fits the campaign’s goals. Discovery and selection happen through conversation and strategic fit in a mere matter of seconds. What a brand can find — and who can find them — is no longer determined by existing relationships or preset deal lists.

This is the shift from biddable to discoverable.

Being discoverable by brands means having a sales agent that makes your inventory visible, well-described, and machine-readable at the moment a buyer is looking. A publisher with a deeply engaged health and wellness audience isn’t competing against every publisher with similar content. They’re competing on whether their specific audience, in their specific context, is the right match for a brand’s specific brief and set of objectives. That’s a more precise and rewarding competitive dynamic for publishers who’ve invested so much in building assets and experiences that are genuinely differentiated.

How agents discover and evaluate inventory — and what determines whether yours gets chosen

In today’s agentic advertising ecosystem, inventory discovery begins with a structured query. A brand’s agent translates a brief into a request — specifying campaign objectives, audience priorities, formats, geography, and brand safety thresholds — and sends it directly to publisher-side sales agents. Those agents then respond with available inventory as structured products: pricing, audience signals, contextual data, and delivery parameters, all evaluated against the original brief.

Selection is based on alignment with campaign intent. Publishers assemble and present their products; the buyer agent evaluates them against their objectives. Publishers with similar supply may be represented very differently depending on how their inventory is packaged and what signals are included. The inventory that most often gets chosen is the inventory that’s clearest about what it is and most aligned to what the buyer needs.

What publisher participation requires — technically and commercially

Participation has two components that work together.

On the technical side, publishers need to make inventory accessible to agent-based queries. This means building or connecting a sales agent — whether managing one directly or working with a provider like Prebid — that can accept structured briefs and return machine-readable responses reflecting current availability and pricing.

AdCP v3.0, recently unveiled, introduces critical changes that make the publisher’s position in an agentic transaction more precise, more legible, and more competitive. These changes include a 19-channel media taxonomy aligned to how buyers plan and allocate budgets, publisher-owned property definitions that create a single source of truth for your inventory, and a Governance Protocol for brand suitability calibration (among other meaningful updates).

On the commercial side, publishers have full control (and room to get creative) in how inventory is packaged and presented. Product structure, pricing logic, and the signals used to describe inventory all shape how it performs once it appears in a response. The richer and more specific that description, the better an agent can evaluate it against the buyer’s intent — and the more competitive your inventory becomes.

Together, these layers determine both publisher inclusion in agentic media buys and their performance within them.

How publishers are getting started

Buyer demand is active and growing. Campaigns are already running through agent-driven workflows. Supply is still developing, which creates a near-term window to enter a forming market rather than a formed one.

Four practical ways to get started:

1. Align internal teams. Sales, ad operations, and product need a shared model of how agentic buying works and what your participation requires. The right internal alignment makes every subsequent step faster.
2. Assess inventory as products, not placements. What can you offer a buyer’s agent? Define your products explicitly — audiences, contextual environments, exclusive formats, forward inventory — and equip them with the signals needed to evaluate them against a brief.
3. Build or connect a sales agent. This is the technical prerequisite for participation. If you’re already in the ecosystem, upgrading to AdCP v3.0 ensures your inventory is fully discoverable as buyer agents adopt new protocol capabilities. If you’re not yet running a sales agent, now is the time to evaluate your options.
4. Engage with the ecosystem. AgenticAdvertising.org is where the norms, standards, and working relationships of this market are being established. The publishers participating now are helping shape what comes next.

The case for moving now

The world’s top brands are already going agentic. According to the IAB’s 2026 Outlook Study, two-thirds of advertisers are now focused on agentic AI for ad buying and campaign execution — what the IAB calls a shift “from AI experimentation to scaled execution.”

Agentic buying systems are building familiarity with the publishers they can reach and work with — based on who has compatible agents, who returns well-structured responses, and who delivers on the deals that get done.

The publishers participating early aren’t just gaining first-mover exposure. They’re learning: refining how their inventory is packaged, deepening their signal coverage, and improving how their agents perform over time. That learning compounds.

Agent-to-agent media buying is real, active, and accelerating. The question for publishers isn’t whether to engage. It’s whether to engage while the ground floor is still accessible. The market is forming now — and the publishers, standards, and relationships taking shape today will define how it operates for years to come.

To go deeper on where agentic advertising is headed, AgenticAdvertising.org is where the industry is building the norms and infrastructure together. For a closer look at the protocol powering publisher participation, explore AdCP at adcontextprotocol.org. And if you’re ready to talk through what this looks like for your inventory specifically, get in touch with Scope3 below.