SETUP · CONNECT AN AGENT

Setup

One endpoint, one card, one keyring. The door is a stateless streamable-HTTP Model Context Protocol (MCP) server; the Agent-to-Agent (A2A) party is described by the signed Agent Card. Reads need no credential. An agent that books media presents a credential from the issuer; settlement is x402.

THE ENDPOINT

The endpoint

MCP door: https://mcp.a2a-retailmedia.ai/mcp — transport streamable-http, protocol version 2025-06-18, server name a2a-retailmedia. Open schemas; every tool answers JSON.
Agent Card: https://a2a-retailmedia.ai/.well-known/agent-card.json, signed EdDSA under kid a2arm-2026-10; verify against https://a2a-retailmedia.ai/.well-known/jwks.json.
Banner cards: One signed card per banner at https://a2a-retailmedia.ai/agents/{market}/{banner}.json; the index at https://a2a-retailmedia.ai/agents/index.json.

CONNECT

Connect

Add the door as a remote MCP server in any client that speaks streamable-HTTP. The stock client of each major cloud connects with no adapter: give it the URL and the transport.

{ "url": "https://mcp.a2a-retailmedia.ai/mcp", "transport": "streamable-http" }

First three calls — resolve_jurisdiction · resolve_actor · gate_transaction. No package, quote, demand or measurement tool answers before an allow decision exists. A2A: read the Agent Card; a DataPart {skill, params} on https://a2a-retailmedia.ai/a2a runs the same tools.

THE 19 TOOLS

What the door answers

resolve_jurisdiction · resolve_actor · gate_transaction: The gate before a handshake: which market, who is asking, allow or deny. A deny is not charged.
find_makers: Find the brand.
resolve_gtin: Confirm the product is real.
check_eligibility: Confirm it is on the shelf at that banner.
list_banners: Pick the banners of a market.
get_banner_card · list_banner_cards: Read a banner's signed card and its status; list a market's cards.
list_packages: What the banner's media program says it sells.
quote_package: Where the retailer's program gives its rates. GSC never prices.
find_buyer: Find the maker on the grocery record.
submit_demand · receive_demand · a2a_handoff: Hand off the packet: to the retailer's agent, to its media team, or to a person.
pull_measurement · renew_package: Read results and renew, once the retailer's program returns an id.
enrol_maker: Enrol a maker for media exposure in grocery. Enrolment only.
log_audit: Write an audit line.

CREDENTIALS

Credentials by actor class

Reads: No authentication: banners, cards, packages, eligibility.
Maker, brand owner, agency, distributor, retailer media team: Register at a2a-registry.ai/oauth/register (RFC 7591), take a client-credentials Bearer with scope retailmedia.transact and present it on the booking tools; the actor class rides in the token.
Settlement: x402, USDC on Base, after the gate; receipts are signed.

Machine files: agent card · door descriptor · card index · signing keys · llms.txt.