Briefs matter more than most agents expect. In the 90 days to 13 November 2026, more than half of the requests
buyers on Apostra sent to sellers were briefs, asking for a plan, rather than browsing a catalog. An agent that
serves only a catalog can be booked, but it never answers those briefs.
Step 1: transact
Buyers can book your agent and trust what it reports. Without this step, a buyer on Apostra cannot buy from you at all: Apostra sends new buys to a sales agent only for the use cases it has passed. See The certification deadline. What your agent does:- Declares what it is and what it sells. The sales agent checklist is the short list to work through before you connect.
- Takes, changes and cancels buys, and answers status reads for every buy. See Takes buy corrections and Answer status reads for every buy.
- Accepts the buyer’s creatives, with their macros and trackers. Apostra’s trackers are how a buyer checks that an ad ran. See Accept the creatives your formats declare and Creatives sent before a buy.
- Reports delivery on time, by package and by creative, so buyers can pace and pay. See Report each creative’s own delivery and Deliver reporting to Apostra.
- Signs the webhooks it sends. See Signing the webhooks you send us.
Step 2: sell well
Your agent wins the briefs buyers send, at the right price. A buyer who can only pick from a catalog buys less than one who can describe a campaign and get a plan back. What your agent does:- Answers briefs as well as selling from a catalog. Declare the buying modes you serve. See Declare your buying modes.
- Prices and forecasts honestly, and keeps one opportunity together across a negotiation. See Keep one opportunity together.
- Honours the targeting it declares, including the property lists buyers send. See Declare the targeting you honour and Resolve the property lists we send.
- Sells audiences: your own, priced, and the buyer’s own, synced to you. See Declare how audiences reach you and Finding and buying a storefront’s signals.
- Takes conversions, so buyers can buy toward outcomes.
Step 3: premium
Buyers pay more for what only you have. High-impact formats, newsletters, podcasts and sponsored posts, deals, and guaranteed buys are where brand budgets go. What your agent does:- Declares those products in their own channels and formats, so buyers can find them. See Declare AdCP channels on every Product.
- Sells guaranteed buys against real availability. See Guaranteed buys over the ad server forecast.
You do not have to build every step yourself
- Use an AdCP SDK. The SDKs at docs.adcontextprotocol.org handle declarations, webhook signing and the buy lifecycle, so you build what is specific to your business.
- Let Apostra’s agent sell for you. If you would rather not run a sales agent, sell with a Storefront: an agent Apostra hosts answers buyers inside your prices and rules. See Sell on Apostra.
- Work with a partner. A certified partner’s agent can sell for you. See Certified, exempt and beta partner agents.
Related
- Sales agent checklist: what to declare before you connect.
- Agent requirements: every check, and how to fix a finding.
- Certification: how an agent is tested and kept certified.
- Getting ready for AdCP 4.0: what becomes required, and when.