TL;DR: Publishers working with autonomous buy-side agents need to define deal parameters their sell-side infrastructure can communicate and enforce. This article explains what that looks like in practice.

The Publisher Challenge with Agentic Buyers

When a buy-side agent approaches a publisher to negotiate inventory, the publisher faces a question their existing infrastructure was not built to answer: how do I communicate my deal terms to a machine, and how do I enforce them without human involvement at every step?

Traditional direct sales require a human sales team to negotiate terms, draft an insertion order, and monitor delivery. Programmatic selling delegates much of this to auction mechanics, floor prices, and deal IDs. Neither model is designed for a situation where a buy-side agent wants to negotiate deal terms directly, in a structured protocol, and produce a shared deal record.

Publishers who want to participate in agentic buying need sell-side infrastructure that can do three things: communicate deal parameters, negotiate within defined limits, and produce a bilateral deal record.

What Deal Parameters Mean for Publishers

In an agentic context, deal parameters are the publisher's equivalent of the buyer's mandate. They define what the publisher's sell-side agent is authorised to accept.

The core parameters a publisher needs to define include:

Price floors. The minimum CPM the sell-side agent will accept for a given inventory type. These can be set at the property level, the placement level, or the audience segment level.

Inventory eligibility. Which properties, placements, and formats are available for agentic buying, and which are reserved for direct sales or preferred programmatic partners.

Brand safety conditions. The content categories and advertiser categories the publisher will and will not accept. These conditions need to be machine-readable so the buy-side agent can verify compatibility before negotiating.

Deal structure preferences. Whether the publisher prefers volume commitments, fixed CPMs, or flexible arrangements, and what the minimum deal size is.

Pacing and delivery requirements. How impression delivery should be paced, and what the publisher's requirements are for impression tracking and discrepancy resolution.

What Infrastructure Is Required

For a publisher to participate in agent-to-agent buying, their sell-side infrastructure needs to support several capabilities.

A sell-side agent. The publisher needs an agent that can receive deal proposals, evaluate them against the publisher's parameters, and respond with acceptance, rejection, or a counter-proposal.

Structured deal communication. The sell-side agent needs to communicate using a protocol the buy-side agent understands. The Agent Communication Protocol (AdCP) is the emerging standard for this.

Bilateral deal record generation. When a deal is agreed, the publisher's infrastructure needs to produce a copy of the deal terms that the publisher holds independently, separate from the marketplace's record.

Audit and reporting integration. The publisher needs to be able to compare agreed deal terms against delivered performance, at the deal level.

How Alkimi Supports Publishers

Alkimi operates as a neutral marketplace. Publishers set their deal parameters within the platform, and Alkimi's infrastructure manages the interaction between buy-side agents and the publisher's supply.

Publishers do not need to build their own sell-side agent from scratch. Alkimi provides the protocol layer, the deal record infrastructure, and the audit trail. The publisher sets parameters; the platform handles the negotiation mechanics.

Both the publisher and the buyer hold a copy of the agreed DealSheet. The publisher can review every deal agreed on their behalf, including the terms, the timestamp, and the buyer identity.

What Publishers Should Prioritise

Publishers evaluating agentic buying infrastructure should start with the parameters that matter most for their business: price protection and brand safety. Getting these right in the initial configuration is more important than the full range of deal parameters.

Once price floors and brand safety conditions are set and tested with a small volume of agentic deals, publishers can expand the parameter set progressively. The goal is to establish a working agentic supply relationship with a small number of trusted buy-side partners before scaling.

Publishers who establish agentic supply infrastructure now will be positioned to receive spend from the growing number of US agency trading desks deploying buy-side agents.