MCP in advertising: how an agent books through an ad server

How an AI agent uses the Model Context Protocol to find ad inventory, create a media buy and settle it: the 19 tools of the Nexbid MCP server, the flow step by step and today's limits.

What this is about Until now, a person books advertising: they open an interface, pick inventory, upload creatives, set a budget and later read the report. An AI agent can perform the same steps if the ad server offers those steps as tools. That is what the Model Context Protocol (MCP) is built for. In 2026, large platforms started opening their systems this way; on 13 May 2026 Adform announced an MCP server that exposes its whole platform. This article is for developers, ad-ops teams and CTOs at publishers and sales houses in the DACH region. It explains how the protocols fit together, which tools the Nexbid MCP server offers, and how a media buy runs from the inventory query to settlement. At the end it lists what does not work today. For context: Nexbid is a two-sided marketplace. Publishers bring content and pages (recipes, articles, reviews), advertisers bring products and campaigns (product feed, budget, bid). Revenue only appears at the match moment: content, product and the intent of the query fit together, and the result is a labelled recommendation. An agent that books works between these two sides. Three protocols, three jobs Discussions about agentic advertising are full of acronyms. For the engineering, three of them matter, and they sit on different layers. MCP (Model Context Protocol) is the transport. It defines how an agent finds a server, which tools the server offers, and how a tool call travels as a JSON-RPC message over HTTP. MCP says nothing about what a "media buy" is. It carries any kind of tool, from a weather lookup to a campaign booking. AdCP (Ad Context Protocol) is the vocabulary for advertising. It is published and governed by AgenticAdvertising.org (AAO), a coalition whose founding members include Yahoo, PubMatic and Scope3. AdCP describes how agents discover, plan, buy, sell and measure media, and it builds on MCP to do so. Tool names such as create_media_buy or list_inventory come from this vocabulary. AdCP does not belong to Nexbid. Nexbid is a member of AAO and implements AdCP. A2A (Agent-to-Agent) is a protocol for communication between agents. Where MCP connects an agent to a tool server, A2A connects an agent to another agent that offers its own capabilities ("skills"). Nexbid runs an A2A endpoint at api.nexbid.dev/v1/a2a. It covers search, product details, categories and purchase intents. Media buying runs over MCP. Alongside these sits the IAB Tech Lab …

Author

Nexbid Engineering

Published

2026-11-08

Topics

Agentic, Ad Tech, Protocol Commerce, Agent Discovery