The IAB Tech Lab Agent Registry is a public directory where companies list the advertising AI agents they bring to market, so buyers, publishers and other agents can find them, see who operates them and learn how to connect. It sits in IAB Tech Lab's Tools Portal, is free for members and non-members, and accepts MCP and A2A agents. A listing shows that a named, reviewed company has put an agent on public record. It does not show that the agent is authorised to act for a particular buyer or publisher, or that it will honour what it agrees.

TL;DR. The Agent Registry answers the first question in any agent-to-agent deal: who operates the software on the other side. According to IAB Tech Lab, each registering company is tied to its GPP ID, every entry is reviewed for validation information, and the registry can be searched through a web interface, a REST API or as an MCP server that agents query directly. A listing is the start of due diligence, not a substitute for it.

What is the IAB Tech Lab Agent Registry?

IAB Tech Lab presents the Agent Registry as the trust and transparency component of AAMP, the Agentic Advertising Management Protocols, its open-source framework for agentic advertising. On its AAMP page, IAB Tech Lab says the registry "establishes a trusted framework for agent identity, verification, and disclosure so participants can confidently understand who (or what) they are transacting with."

Anyone can browse the registry: the public registry site says visitors can explore listings without a Tools Portal login, while registering or updating an agent requires signing in. IAB Tech Lab named Equativ and PubMatic among the early supporters registered at launch, and says the registry's roadmap is set by its Agentic Task Force.

Why do agent discovery and identity matter when software commits budget?

When a person agrees a deal, the counterparty is a known business. When an agent agrees a deal, the counterparty is an endpoint. Without an independent record of who operates that endpoint, nobody can say who is accountable for what the agent commits to.

Programmatic has met this problem before. ads.txt in 2017 and sellers.json in 2019 gave buyers public, machine-readable declarations of who could sell a publisher's inventory and who the sellers in a supply chain were. The Agent Registry addresses the equivalent first step for agents: a public record linking an agent to a reviewed company.

Equativ's Chief Innovation Officer, Curt Larson, framed the requirement at launch: "It's critical that we do so in a way that enables the existing measurement, transparency, safety, and accountability mechanisms to continue to function."

What does an Agent Registry listing contain?

According to IAB Tech Lab, a registering company defines its agent, assigns it to Tech Lab categories, describes its purpose and capabilities, states whether it is an MCP or A2A agent, and sets a maturity level. Categories named at launch include Demand Side Platform, Identity Resolution, Measurement & Attribution, Customer Data Platform and Consent Management.

The public registry adds operational detail: the operating company and domain, the endpoint, whether the agent runs remotely, locally or privately, the tools it exposes, and documentation and support links.

Each listing shows three verification marks: domain, GPP and endpoint. IAB Tech Lab says every registering company is associated with its GPP ID, which includes its IAB TCF Global Vendor List IDs for validation, and that it reviews each entry to make sure the necessary validation information is provided. The same validation tools are available in the Tools Portal for users to run their own checks.

What does a registry listing not prove?

Authorisation for a property. A listing shows who operates an agent, not which publisher's inventory it may sell. IAB Tech Lab's launch post listed the ability "to verify that seller agent actually represents a property (like ads.txt for agents)" as a roadmap feature.

Authority for a principal. A buy-side agent from a technology vendor may act for many advertisers. The listing does not say which client it represents in a negotiation, or what that client has authorised it to spend.

Behaviour. Maturity levels and capability lists are the operator's own description. An endpoint check shows the endpoint responds, not that the agent prices honestly or delivers what it agrees.

Conformance. There is no AAMP compliance certification. A listing does not state that an agent implements any AAMP component correctly.

The deal. A registry records agents, not agreements. What was agreed, at what price and under which measurement terms has to be recorded somewhere both parties can retrieve.

AgenticAdvertising.org, which publishes AdCP, approaches the same discovery and authorisation questions through its own registry and a publisher-hosted adagents.json file.

How does the registry relate to AAMP's registry-agent-example?

The AAMP repository on GitHub lists registry-agent-example as a component that "demonstrates agent discovery, registration, and coordination patterns." Its README describes a TypeScript agent, built with Google's Agent Development Kit, that connects to the Tech Lab registry's MCP server to browse entries, search the registry and return details about registered agents and MCP servers. Its code connects in read-only mode.

The pattern is that agents call the registry themselves. IAB Tech Lab's launch post gives sample queries such as "give me a list of seller agents". A buyer agent can shortlist counterparties before a human has looked at anything, which is why the listing data, and its limits, matter.

What should a company check before listing an agent?

Confirm the company's GPP ID and TCF Global Vendor List IDs are current.
Choose the categories that match what the agent does, not every one it might touch.
State the maturity level honestly; counterparty agents may filter on it.
Describe the purpose plainly: what the agent does, for whom, and what it will not do.
Keep the endpoint reachable and the documentation and support links working.

What should a buyer or publisher check before trusting a listed agent?

Do the company and domain in the listing match the company the agent claims to be?
Which verification marks does the listing show, and are any missing?
Is the maturity level suitable for real spend, or only for testing?
Which advertiser or publisher has authorised this agent, and where is that recorded?
Which AAMP components and versions does it use, and for which deal types?
Where will agreed terms be recorded, and can both sides retrieve the same version?

Take a hypothetical buyer agent with a £30,000 mandate for a news publisher's video inventory. It finds two listed seller agents describing that publisher's inventory, both verified, both run by real companies. The registry alone cannot say which one the publisher has authorised, so the checks have to go further before money moves.

Alkimi's neutral marketplace is built for that next step: it works within IAB Tech Lab's AAMP framework, its own agent is listed in the IAB Tech Lab Agent Registry, it checks that connecting agents are authorised by the buyer or publisher they represent, and it is being built to be AdCP compatible. Agreed deals are recorded on a shared DealSheet both parties hold, with humans keeping approval rights at the deal level.

Frequently asked questions

Who runs the IAB Tech Lab Agent Registry?

IAB Tech Lab, as part of its Tools Portal and AAMP framework. It is free for members and non-members.

How do agents use the registry?

The registry is an MCP server with a REST API, so agents can query it directly. AAMP's registry-agent-example shows how.

Does an Agent Registry listing mean an agent is AAMP compliant?

No. There is no AAMP compliance certification. A listing shows who operates the agent, not that it implements AAMP correctly.

Does a listing prove a seller agent can sell a publisher's inventory?

No. IAB Tech Lab listed verification that a seller agent represents a property as a roadmap feature, so authorisation still has to be confirmed separately.

What Is the IAB Tech Lab Agent Registry? How Do Companies List Agents and How Do Buyers and Publishers Use It?