AdCP — Accounts and agents

AdCP distinguishes four entities in every billable operation:

Entity	Question	How identified
Brand	Whose products are advertised?	Brand reference: `domain` + optional `brand_id` and commercial-identity `countries[]` (brand.json)
Account	Who gets billed? What rates apply?	Account reference
Operator	Who operates on the brand’s behalf?	Domain (e.g., `pinnacle-media.com`)
Agent	What software is placing the buy?	Authenticated session

Brand — The advertiser whose products or services are promoted. Identified by a brand reference (domain + optional brand_id and ISO country countries[]), resolved via /.well-known/brand.json. Countries distinguish commercial advertiser identities without becoming delivery targeting. Account — A billing relationship between a buyer and seller. Determines rate card, payment terms, credit limit, operational timezone, and who receives invoices. Every billable operation requires an account reference — a seller/storefront-assigned account_id when the seller or upstream platform owns the canonical account namespace, or an advertiser natural key (brand, operator, optional operator_unit, fixed currency, buyer-selected timezone, sandbox) for buyer-declared accounts. Operator — The entity driving buys — an agency trading desk, the brand’s internal team, or another entity acting on behalf of the advertiser. Identified by domain and verifiable via authorized operators in brand.json. Agent — The software placing buys and managing campaigns. Authenticates with the seller and may operate on behalf of multiple operators and brands. See Accounts Protocol overview for the full commercial model and sync_accounts for the task reference.

What sellers declare

Sellers configure the account section of get_adcp_capabilities: 1. Which billing models do you support? (supported_billing) The buyer must pass one of these values as billing in every sync_accounts entry. The seller either accepts or rejects.

Billing	Who is invoiced	Use case
`operator`	Operator (agency or brand buying direct)	Operator buying on their own terms
`agent`	Agent	Agent consolidates billing across brands
`advertiser`	Advertiser directly	Operator places orders but advertiser pays (common on social platforms and in DACH B2B workflows)

This is an account-level invoiced-party choice. It does not select a payment rail, clearing intermediary, or settlement route for an individual media buy; AdCP payment and settlement remain out of protocol. 2. Which account currency models do you support? (supported_account_currency_modes) Sellers implementing AdCP 3.2 advertiser-account provisioning advertise one or both values. The field remains optional in the shared 3.x wire schema so existing 3.0 and 3.1 responses continue to validate; absence means the older seller’s currency model is not discoverable and does not imply support for either mode.

Mode	Provisioning behavior
`fixed`	Include one immutable ISO 4217 `currency`; it participates in the advertiser account natural key.
`per_media_buy`	Omit account `currency`; select currency on each proposal or media buy.

When both are present, the buyer selects the model by including or omitting currency. 3. Do you require operator-level auth? (require_operator_auth) This field determines the authentication model and the account reference shape: When false (default) — buyer-declared accounts: the seller trusts the agent. The agent authenticates once and declares accounts via sync_accounts. On subsequent requests, the buyer passes the natural key (brand + operator) and the seller resolves internally. See Seller walkthrough: buyer-declared accounts for how the seller identifies the agent and where each field comes from. When true — account-id namespaces: each operator must authenticate with the seller directly. The agent obtains a credential per operator — via OAuth using the seller’s authorization_endpoint, or via API key out-of-band. Subsequent requests pass a seller-assigned account_id. If a credential may access more than one account, the seller MUST expose list_accounts and the buyer MUST resolve an explicit account before the first account-scoped request. If a credential is bound to exactly one account, the seller SHOULD expose list_accounts returning that singleton; a seller MAY omit list_accounts only when it supplies the same explicit account ID through another declared path or out-of-band onboarding. For sandbox, the path follows the account namespace: account-id namespaces use pre-existing test accounts from list_accounts or out-of-band setup; buyer-declared accounts use sync_accounts with sandbox: true and reference by natural key. Sellers can also declare account_financials: true to expose account-level financial data (spend, credit, invoices) via get_account_financials. This only applies to operator-billed accounts. Example capabilities:

{
  "account": {
    "require_operator_auth": false,
    "supported_billing": ["operator", "agent"],
    "supported_account_currency_modes": ["fixed", "per_media_buy"]
  }
}

Sellers that support advertiser billing declare it explicitly:

{
  "account": {
    "require_operator_auth": false,
    "supported_billing": ["operator", "agent", "advertiser"],
    "supported_account_currency_modes": ["fixed", "per_media_buy"]
  }
}

These fields combine into common patterns.

Seller patterns

Which kind of platform are you buying from? That determines the account setup pattern.

Platform type	Account pattern	`require_operator_auth`	`supported_billing`
Social / walled garden	Upstream-managed account-id namespace	`true`	`["operator"]`
Direct publisher	Buyer-declared accounts	`false`	`["operator"]` or `["operator", "agent"]`
DSP / programmatic	Buyer-declared accounts	`false`	`["agent"]`

The operator already has an account on the platform — an ad account, a business manager, a self-serve dashboard. The upstream platform owns the canonical account namespace accessible to that credential. The agent obtains the operator’s credentials (via OAuth or API key), opens a per-operator session, resolves an explicit account through list_accounts, and uses the returned account_id values. The platform bills the operator directly. Capabilities:

{
  "account": {
    "require_operator_auth": true,
    "supported_billing": ["operator"],
    "supported_account_currency_modes": ["fixed"],
    "authorization_endpoint": "https://seller.example.com/oauth/authorize"
  }
}

Buyer workflow:

Call get_adcp_capabilities — see require_operator_auth: true and authorization_endpoint
For each operator: a. Obtain operator’s credential (OAuth via authorization_endpoint, or API key out-of-band) b. Open a new session with the operator’s credential c. Call list_accounts to discover accounts visible to that credential
Human or policy selects the correct account from the list
Call get_products / create_media_buy with the operator’s session and { "account_id": "..." }

list_accounts response:

{
  "accounts": [{
    "account_id": "acc_spark_social_001",
    "name": "Spark paid social",
    "brand": { "domain": "nova-brands.com", "brand_id": "spark" },
    "operator": "pinnacle-media.com",
    "status": "active",
    "billing": "operator",
    "account_scope": "operator_brand"
  }]
}

Subsequent calls use the discovered ID:

{
  "account": { "account_id": "acc_spark_social_001" }
}

Key point: The operator’s credential — not the agent’s — authorizes all calls in that session. The buyer does not declare or create accounts through AdCP in the 3.0.x account-id model; list_accounts mirrors the upstream namespace. If the seller exposes sync_accounts, it is only for settings updates against an existing account_id, not natural-key provisioning, unless a future explicit capability declares account-id provisioning.

Direct publisher

The publisher trusts the agent but bills the operator directly. The agent sets up accounts via sync_accounts — no per-operator login needed. Accounts may require human approval (credit checks, legal agreements) before becoming active. Many publishers also accept agent billing (supported_billing: ["operator", "agent"]). The buyer chooses per account — operators with a direct relationship use billing: "operator", everything else uses billing: "agent". If the seller doesn’t support the requested billing for a particular account, it rejects the request and the agent re-submits with a different model. Capabilities:

{
  "account": {
    "supported_billing": ["operator", "agent"],
    "supported_account_currency_modes": ["fixed", "per_media_buy"]
  }
}

Buyer workflow:

Call get_adcp_capabilities — see require_operator_auth absent (defaults to false)
Call sync_accounts for each brand/operator pair
Wait for account status active — may require human to complete credit/legal at setup.url
Call get_products with account reference
Call create_media_buy with account reference

sync_accounts request — brand buying direct:

{
  "accounts": [{
    "brand": { "domain": "acme-corp.com" },
    "operator": "acme-corp.com",
    "billing": "operator"
  }]
}

Seller acknowledges the request but requires setup before provisioning:

{
  "accounts": [{
    "brand": { "domain": "acme-corp.com" },
    "operator": "acme-corp.com",
    "action": "created",
    "status": "pending_approval",
    "billing": "operator",
    "account_scope": "brand",
    "setup": {
      "url": "https://seller.example.com/advertiser-onboard",
      "message": "Complete advertiser registration and credit application"
    }
  }]
}

The seller has acknowledged the relationship (brand: "acme-corp.com", operator: "acme-corp.com", billing: "operator"), but the account is pending review before it becomes active. A human at Acme Corp completes the setup at the URL. To check progress, the agent either:

Re-calls sync_accounts with the same natural key — the seller returns the updated status
Receives a webhook notification if push_notification_config was provided in the request

Key point: pending_approval is the normal path. Every buyer needs a direct relationship with the seller. Billing rejection — operator billing not available: The seller supports operator billing in general, but may not support it for every operator. Here, the agent requests operator billing for an operator without a direct relationship:

{
  "accounts": [{
    "brand": { "domain": "acme-corp.com" },
    "operator": "acme-corp.com",
    "billing": "operator"
  }]
}

Seller rejects the request because this operator has no direct billing relationship:

{
  "accounts": [{
    "brand": { "domain": "acme-corp.com" },
    "operator": "acme-corp.com",
    "action": "failed",
    "status": "rejected",
    "errors": [{
      "code": "BILLING_NOT_SUPPORTED",
      "message": "Operator billing is not available for this account. Re-submit with billing: \"agent\"."
    }]
  }]
}

The agent re-submits with billing: "agent" or informs the buyer that operator billing is not available with this seller. Billing is never silently remapped.

DSP / programmatic

All billing flows through the agent. The agent has a standing relationship with the platform and consolidates billing across all brands and operators. Accounts are created instantly — no human approval needed. Capabilities:

{
  "account": {
    "supported_billing": ["agent"],
    "supported_account_currency_modes": ["per_media_buy"]
  }
}

Buyer workflow:

Call get_adcp_capabilities — see supported_billing: ["agent"]
Call sync_accounts for each brand/operator pair with billing: "agent"
Accounts are active immediately — no human approval needed
Call get_products / create_media_buy with account reference

sync_accounts request:

{
  "accounts": [{
    "brand": { "domain": "nova-brands.com", "brand_id": "spark" },
    "operator": "pinnacle-media.com",
    "billing": "agent"
  }]
}

Account active immediately:

{
  "accounts": [{
    "brand": { "domain": "nova-brands.com", "brand_id": "spark" },
    "operator": "pinnacle-media.com",
    "action": "created",
    "status": "active",
    "billing": "agent",
    "account_scope": "operator_brand"
  }]
}

Key point: The agent receives a single consolidated invoice. Per-brand accounts give reporting granularity but billing is centralized.

Authorized operators

Brands declare who can represent them in /.well-known/brand.json via the authorized_operators field. Sellers SHOULD verify operators against this when processing sync_accounts.

{
  "house": {
    "domain": "nova-brands.com",
    "name": "Nova Brands"
  },
  "brands": [
    { "id": "spark", "names": [{"en": "Spark"}] },
    { "id": "glow", "names": [{"en": "Glow"}] }
  ],
  "authorized_operators": [
    {
      "domain": "pinnacle-media.com",
      "brands": ["spark", "glow"],
      "countries": ["US", "GB", "DE"]
    },
    {
      "domain": "summit-agency.jp",
      "brands": ["spark"],
      "countries": ["JP"]
    },
    {
      "domain": "nova-brands.com",
      "brands": ["*"]
    }
  ]
}

Field	Required	Description
`domain`	Yes	Operator’s domain
`brands`	Yes	Brand IDs this operator can represent. `["*"]` means all brands.
`countries`	No	ISO 3166-1 alpha-2 country codes. Omit for global authorization.

Verification flow

Resolve {brand.domain}/.well-known/brand.json
Check authorized_operators for matching domain with the brand in brands
If found → proceed (account may still need credit/legal approval)
If not found → reject the account (action: "failed") or return pending_approval for manual review

Verification is a trust signal, not a gate. Finding the operator in brand.json lets the seller fast-track provisioning. If the operator isn’t listed, the seller can still approve through its own review process. Self-authorization is implicit. When the operator domain matches the brand’s domain, the brand is operating directly — no listing in authorized_operators is needed. authorized_operators models the interface between the brand and whoever operates on its behalf. It does not model internal agency hierarchies.

Buyer-agent identity

authorized_operators tells the seller whether an operator is allowed to represent a brand. It doesn’t tell the seller who the agent placing the call is, or what commercial relationship is on file with that agent. Those are different questions, and the seller checks both before provisioning. Two layers run on every sync_accounts request:

Layer	Question	Where it lives
Agent identity	Which buyer agent issued this request?	The seller’s onboarding record, looked up by signed-request `agent_url` (when request signing is in use) or by the bearer / API-key / OAuth credential the agent presented. Signature or credential establishes identity; authorization is a separate check.
Brand-operator authorization	Is the operator named in the request authorized to act for the brand?	`brand.json` `authorized_operators` (above). Verified whether the request is signed or not.

Both layers MUST pass. A signed request from an onboarded agent for an unauthorized operator gets rejected on the brand-operator check; a request from an unrecognized agent for an authorized operator gets rejected on the identity check. Sellers that advertise request_signing.required_for on sync_accounts reject unsigned traffic at the identity layer; sellers that don’t advertise it MAY still require an established credential mapping before agent-billable values are accepted. The brand-operator check runs against the seller’s cached brand.json per Operator revocation and caching — revocation is eventual. Sellers performing high-value or first-time-on-this-brand provisioning SHOULD bypass the cache to close the TOCTOU window. SDK naming for the brand-operator authorization Protocol. SDKs that surface a typed Protocol for the brand-operator check (for adopters to plug their own resolver into) SHOULD name it after the file consulted: BrandAuthorizationResolver (or equivalent in idiomatic casing). The file is brand.json/authorized_operators — the brand-side declaration of who may represent the brand. SDKs SHOULD NOT name this Protocol after adagents.json, which is publisher-side / data-provider-side and models a different relationship (which sales agents may sell that publisher’s inventory). Naming the buyer-side resolver AdagentsResolver confuses the two surfaces and locks adopters into the wrong mental model. This is a spec-side recommendation; SDK conventions track upstream. The agent’s commercial state is offline. Whether a buyer agent is passthrough-only (no payments relationship — only the operator can be invoiced) or agent-billable (the agent can be invoiced directly) is recorded in the seller’s onboarding system, the same way operator account creation is. Provisioning that record — contract, KYC, payment terms, billing entity capture — is out of scope for AdCP. What’s in scope is two on-wire consequences:

Runtime billing gate. A passthrough-only agent that submits billing: "agent" or billing: "advertiser" is rejected with BILLING_NOT_PERMITTED_FOR_AGENT and an error.details.suggested_billing of operator. See Billing and Account Setup for the recovery contract.
Per-agent defaults. Sellers MAY pre-fill payment_terms, billing_entity, rate-card linkage, and credit limit from the buyer agent’s onboarding record when provisioning new accounts under that agent. Per-account values on the sync_accounts request always take precedence over per-agent defaults — the buyer can override per row. The per-agent layer is a recommended implementation pattern (it mirrors how SSPs maintain buyer_id / seat_id rows for OpenRTB DSPs); smaller publishers MAY collapse to seller-wide defaults until they have receivables ops that distinguish per-agent terms.

Account references

Every account-scoped operation accepts an account object instead of a flat account_id string. The seller’s require_operator_auth capability determines the auth model and reference shape; tool exposure distinguishes upstream-managed account_id namespaces from seller-defined IDs supplied out-of-band.

Sellers that support caller-scope introspection attach an optional authorization object to each per-account entry in sync_accounts and list_accounts responses — listing the tasks and request fields this caller is allowed to use on the account, plus any standard named scope (e.g., attestation_verifier). See Caller authorization for the full shape and semantics.

Account-id namespaces (`require_operator_auth: true`)

Accounts are managed outside of AdCP. The advertiser creates an account on the seller’s platform, grants the operator permission to manage it, and the buyer passes a seller-assigned account_id. The agent is not involved in account creation or billing setup — those are handled between the advertiser, operator, and seller directly. Typical sellers: Social platforms, self-serve ad platforms — anywhere the advertiser already has an account. Upstream-managed workflow:

Advertiser creates an account on the seller’s platform (out-of-band)
Advertiser grants the operator permission to manage the account (out-of-band)
Agent calls list_accounts to discover available accounts
Human selects the correct account from the list
Agent passes { "account_id": "acc_acme_001" } on every request (get_products, create_media_buy, etc.)

list_accounts is mandatory when the authenticated credential may access more than one account because the upstream owns the namespace. When the credential is bound to exactly one account, sellers SHOULD still expose list_accounts returning that singleton so SDKs can auto-select it and send explicit { "account_id": "..." } on required-account calls. sync_accounts provisioning is out of scope for account-id namespaces in 3.0.x unless a future explicit capability declares it; if sync_accounts is exposed today, it is settings-update mode for an existing account_id. Seller-defined workflow: Some sellers use account_id without exposing an account discovery surface. In that pattern, the seller gives the buyer an account ID during onboarding or configuration, and the buyer passes that ID on account-scoped calls. Absence of list_accounts means there is no protocol namespace to discover; it does not mean the buyer should try to provision by natural key.

Buyer-declared accounts (`require_operator_auth: false`)

The agent manages the buying relationship. It calls sync_accounts to tell the seller who’s advertising, who’s operating on the brand’s behalf, and who’s paying. The seller provisions accounts and responds with status — the account IDs are a byproduct of the declaration, not something the buyer needs to know upfront. Buyer-declared-account sellers SHOULD also expose list_accounts as the recovery read for stateless buyers. Replaying sync_accounts is not a cold-start recovery mechanism when the buyer has lost the advertiser natural keys required to compose that replay. list_accounts returns those acknowledged natural-key fields so they round-trip into later calls; it does not make the seller-issued account_id mandatory. Typical sellers: Traditional publishers, retail media networks, DSPs — anywhere the buying relationship is established programmatically. sync_accounts is the declaration tool. Each entry is a set of flags that tells the seller what the buyer needs:

Flag	What it tells the seller
`brand` (`domain` + optional `brand_id`/`countries[]`)	Which commercial advertiser entity is advertising; countries do not target delivery
`operator`	Who operates on the brand’s behalf (agency, trading desk, or the brand itself)
`operator_unit`	Optional operator-owned business unit, seat, or platform account; stable `id` plus mutable display `name`
`currency`	Optional immutable account currency when the seller’s advertiser object is currency-bound
`billing`	Who gets the invoice — `operator`, `agent`, or `advertiser`
`billing_entity`	Structured business entity details for the party responsible for payment — legal name, VAT ID, tax ID, address, contacts, and bank details. Used for formal B2B invoicing. Bank details are write-only (never echoed in responses).
`payment_terms`	Payment terms for this account (`net_15`, `net_30`, `net_45`, `net_60`, `net_90`, `prepay`). The seller must accept these terms or reject the account — terms are never silently remapped.
`sandbox`	Whether this is a sandbox (test) account — no real spend. Only used with buyer-declared accounts; account-id namespace sandboxes are pre-existing and discovered through `list_accounts` or supplied out-of-band.

Every combination of flags that might require the seller to do something different — bill a different entity, set up a different rate card, create a sandbox — is a distinct declaration.

Billing entity and invoice recipient

For markets that require structured invoicing data (e.g., EU B2B transactions requiring VAT IDs), the billing_entity on an account provides the default business entity details for whoever billing points to. This includes legal name, tax identifiers, postal address, billing contact, and bank details. On individual media buys, an invoice_recipient can override the account default — useful when a specific campaign should be billed to a different party. When invoice_recipient differs from the account default and the account has governance_agents, the seller MUST include it in the check_governance request so the governance agent can approve or reject the billing redirect. Workflow:

Agent calls sync_accounts with one or more declarations
Seller provisions or links accounts for each, responds with status:
- active — ready to use
- pending_approval — seller reviewing (human may need to visit setup.url)
- rejected — seller declined the request
For subsequent requests, pass the account reference:
- Buyer-declared accounts (require_operator_auth: false): pass the natural key { "brand": { "domain": "acme-corp.com" }, "operator": "pinnacle-media.com" }
- Account-id namespaces (require_operator_auth: true): pass { "account_id": "acc_acme_001" } (discover via list_accounts for upstream-managed namespaces, or receive out-of-band for seller-defined namespaces)
- Sandbox (buyer-declared): pass the natural key with sandbox: true (declared via sync_accounts)
- Sandbox (account-id namespace): pass { "account_id": "test_acc_001" } (pre-existing test account, discovered via list_accounts or supplied out-of-band)
When anything changes (billing model, new brand, new operator), call sync_accounts again
After a cold start, call list_accounts to recover previously acknowledged relationships when the seller exposes the recommended read surface

The agent may be directly responsible for billing when billing is "agent". When billing is "operator" or "advertiser", the agent facilitates but is not the invoiced party. The seller may require human approval before activating accounts.

Natural key semantics

The tuple (brand, operator, operator_unit.id, currency, timezone, sandbox) identifies the advertiser object in the seller system. The nested brand carries domain, optional brand_id, and optional ISO country countries[]; these countries qualify commercial identity and never target delivery. operator_unit identifies the operator’s own business unit, agency seat, or buying-platform account. Its stable id participates in identity, while its optional name is display metadata and may change without creating a new account. currency participates only when the seller’s advertiser object is locked to one currency. timezone participates only when the seller requires the buyer to select an immutable account timezone during provisioning. Omit either qualifier when its capability mode does not apply. This separates two account namespaces that must not be conflated: operator_unit.id is assigned by the buyer-side operator, while account_id is assigned by the AdCP seller/storefront. Both may be opaque values, but they identify different objects and are not interchangeable. See sync_accounts task reference for the full request/response schema.

Account status

Status	Meaning	Next step
`active`	Ready to use	Place buys on this account
`pending_approval`	Seller reviewing	Human may need to visit `setup.url`. Poll `list_accounts` for updates.
`rejected`	Seller declined the request	Review rejection reason, adjust and re-sync, or contact seller
`payment_required`	Credit limit reached	Add funds or route spend to other accounts
`suspended`	Was active, now paused	Contact seller
`closed`	Was active, now terminated	—

Account scope

The agent requests accounts by natural key — (brand, operator). The seller decides what granularity to assign. The account_scope field in the response tells the agent how the seller resolved the request:

Scope	Meaning	Example
`operator`	One account for all brands under this operator	Agent sends (Pinnacle Media, Acme) and (Pinnacle Media, Nova) — seller maps both to the Pinnacle Media account
`brand`	One account for this brand regardless of operator	Agent sends (Acme, Pinnacle Media) and (Acme, Summit Agency) — seller maps both to the Acme account
`operator_brand`	Dedicated account for this operator+brand pair	Agent sends (Pinnacle Media, Acme) — seller creates a specific Acme-via-Pinnacle account
`agent`	Agent-scoped account with no brand- or operator-specific split	Agent sends any brand — seller maps the request to the standing agent-scoped account

The agent does not choose the scope — the seller assigns it based on its own account policy. An agent requesting (brand: {domain: "acme-corp.com"}, operator: "pinnacle-media.com") might receive an operator-scoped account, a brand-scoped account, or a dedicated operator_brand account depending on the seller. When multiple natural keys resolve to the same scope, the account_scope explains why. For buyer-declared accounts (require_operator_auth: false), use the complete natural key (brand + operator + optional operator_unit, fixed currency, buyer-selected timezone, and sandbox) on subsequent requests. A seller may also return an account_id from sync_accounts as its internal handle, but the seller MUST continue accepting the natural-key AccountRef for every account provisioned this way and MUST return its natural-key fields from list_accounts. For account-id namespaces (require_operator_auth: true), discover seller/storefront account IDs via list_accounts for upstream-managed namespaces, or receive them out-of-band for seller-defined namespaces — including sandbox test accounts.

Seller walkthrough: buyer-declared accounts

This walkthrough is for a seller that declares require_operator_auth: false (or omits it). It covers how the seller identifies the calling agent, where the account’s operator comes from, and which error applies when. Three identities show up on every request. Keep them apart:

Identity	Where the seller gets it	Example
Calling agent	The transport: a verified request signature, or a credential the seller issued at onboarding	`https://agent.orbit-buying.example/mcp`
Agent’s operator	The brand.json that lists the agent in `agents[]`, meaning whoever runs the agent	`orbit-buying.example`
Account operator	The request payload: `accounts[].operator` on `sync_accounts`, `account.operator` on later calls	`pinnacle-media.com`

1. Onboard the agent

Before the agent’s first account-scoped call, the seller records the agent in its onboarding system: the agent’s canonical URL, how it authenticates, and its commercial state (see Buyer-agent identity).

Signed requests. The buyer gives the seller its agent URL during onboarding. From that URL, the seller runs brand_json_url discovery: capabilities, then identity.brand_json_url, then the brand.json agents[] entry, then jwks_uri. It indexes each kid in that JWKS against the agent’s canonical URL. Rebuild the index whenever you refresh an agent’s JWKS or brand.json, so a rotated kid still resolves and a delisted agent drops out. That cache is bounded by the revocation polling interval.
Seller-issued credential. The seller issues an API key or OAuth client and maps it to the agent in the onboarding record. Before mapping a credential to an agent URL, confirm the counterparty controls that agent, for example with a signed onboarding request from it.

For now, the agent URL has to come from outside the request: onboarding, or a registry cache the seller trusts. A signed request carries only a keyid. Each signer picks its own keyid values, and nothing namespaces them, so a seller can’t map a keyid it has never seen to an agent URL. AdCP 3.2 doesn’t put the signer’s agent URL on the wire. A discoverable signer agent URL is under discussion in #7817.

2. Identify the caller on each request

Signed request: the verifier resolves the keyid against the agents it has onboarded. The keyid has to resolve under exactly one canonical agents[].url (verifier checklist, step 7). A keyid that isn’t in any onboarded agent’s JWKS, even after the one refetch step 7 allows, fails with request_signature_key_unknown. A keyid that more than one onboarded agent publishes also fails. The verifier never picks one, and never tries each agent’s keys in turn. Agents that share a JWKS can’t be told apart by signature alone, so use a seller-issued credential for them. On success, the authenticated caller is the canonical agent URL. It isn’t the keyid, the domain, or the JWKS URI (Agent identity).
Unsigned request with a seller-issued credential: the seller looks up the credential in its onboarding record, and the mapped agent is the caller.

Nothing in the request body identifies the caller.

3. Read the account operator from the request

The authenticated caller is the agent. The operator belongs to the account the agent names in the payload. One agent often acts for many operators. Here one buying agent, with one signing identity, declares accounts for two agencies:

{
  "idempotency_key": "sync-7f3c2a90-4d1e-4b8a-9c55-2e61f0a7b3d4",
  "accounts": [
    { "brand": { "domain": "nova-brands.com", "brand_id": "spark" }, "operator": "pinnacle-media.com", "billing": "agent" },
    { "brand": { "domain": "acme-corp.com" }, "operator": "summit-agency.jp", "billing": "agent" }
  ]
}

The seller takes operator from each entry, and later from account.operator. It doesn’t substitute a value from the transport, such as the agent URL, the agent’s brand.json domain, or an operator field an SDK attaches to the authenticated principal. If it did, both accounts would be attributed to orbit-buying.example instead of their agencies, and invoices would go to the wrong party. Two agencies buying the same brand through this agent would also share one account and see each other’s buys and reporting. Authentication still limits what the payload can reach. On calls after provisioning, each account the agent references has to be in that agent’s authorized set (Agent and account isolation). This matches Tenant resolution: the authenticated principal decides which accounts are reachable, and the account reference only selects one. For each sync_accounts entry the seller also runs the brand-operator check and checks the agent’s commercial state against the requested billing. sync_accounts is how an account enters the calling agent’s authorized set. The brand-operator check shows that the operator may represent the brand. It doesn’t show that this agent acts for that operator. If the seller maps a declaration onto an account another agent already uses, the caller gets every object bound to that account. Decide that deliberately before joining an existing account, for example by keeping accounts per agent or confirming out of band.

4. Discover products with the natural key

Once sync_accounts returns status: "active", the agent sends the same natural key on get_products:

{
  "buying_mode": "brief",
  "brief": "Q3 awareness for Spark in the US",
  "account": {
    "brand": { "domain": "nova-brands.com", "brand_id": "spark" },
    "operator": "pinnacle-media.com"
  }
}

When account.required_for_products is true, get_products needs this account. Otherwise the account is optional and selects account-specific pricing. A seller can instead provision lazily on the first account-scoped request, but only when billing and other required settings are clear from its capabilities or onboarding defaults. Such a seller still has to accept the natural key and expose list_accounts. If it needs buyer input before the account is usable, it has to expose sync_accounts (see require_operator_auth).

5. Which error applies when

Authentication resolves first. Signature failures are transport errors, returned as 401 with WWW-Authenticate: Signature error="<code>" (transport error taxonomy). Everything after that is an AdCP error: task-level errors[], or on sync_accounts the per-entry accounts[].errors with action: "failed".

Request	Result
`Signature` or `Signature-Input` present without the other, or malformed	`request_signature_header_malformed`. The seller doesn’t fall back to other credentials.
Signed, and fails the verifier checklist (unknown `keyid`, bad window, bad digest, and so on)	The checklist’s code, such as `request_signature_key_unknown` (also `request_target_uri_malformed` or `request_body_malformed`). The seller doesn’t fall back to other credentials. Exception: for an operation in `warn_for` (or a method in `protocol_methods_warn_for`), a well-formed signature that fails is logged, establishes no signer identity, and the request continues only if another credential authenticates it.
Unsigned. No credential the seller accepts for this operation. Operation is in `required_for`, or its JSON-RPC method is in `protocol_methods_required_for`	`request_signature_required`. This applies even if an unrecognized bearer token was sent.
Unsigned, the seller supports request signing, and the payload carries a webhook `authentication` block (`accounts[].notification_configs[].authentication`, `push_notification_config.authentication`)	`request_signature_required`, even with a valid credential (webhook callbacks)
Unsigned, with a credential the seller accepts for this operation	Authenticated through that credential. This holds for `required_for` operations too, unless the payload carries a webhook `authentication` block (previous row), or the seller configured that authenticator to reject the operation (composition with fallback authenticators).
Unsigned, the operation needs authentication and doesn’t require a signature, and no credentials	`AUTH_MISSING`
Unsigned, the operation doesn’t require a signature, and the credential was presented but rejected	`AUTH_INVALID`
Authenticated agent is suspended or blocked	`AGENT_SUSPENDED` or `AGENT_BLOCKED`
Requested `billing` not available	`BILLING_NOT_SUPPORTED`, or `BILLING_NOT_PERMITTED_FOR_AGENT` for a passthrough-only agent
Natural key doesn’t resolve (and the seller doesn’t provision lazily), or resolves to an account outside the agent’s authorized set	`ACCOUNT_NOT_FOUND`. The response is the same in both cases, so it doesn’t reveal whether the account exists.
Former natural key retired by an account rekey, and the caller is authorized for the current account	`ACCOUNT_MOVED`, with `details.current_account`
Natural key matches more than one account in the agent’s authorized set	`ACCOUNT_AMBIGUOUS`
An account in the authorized set is found, but its state blocks the call	`ACCOUNT_SETUP_REQUIRED`, `ACCOUNT_SUSPENDED`, or `ACCOUNT_PAYMENT_REQUIRED` (Error codes)

Resolve and disambiguate only within the agent’s authorized set. To the caller, an account outside that set doesn’t exist.

Error codes

Code	When returned	Resolution
`ACCOUNT_REQUIRED`	Multiple accounts; seller can’t determine which	Pass `account_id` in the account reference
`ACCOUNT_NOT_FOUND`	`account_id` doesn’t exist or agent lacks access	Check account reference, re-run `sync_accounts`
`ACCOUNT_SETUP_REQUIRED`	Natural key resolved but account needs setup	Check `details.setup` for URL/message
`ACCOUNT_AMBIGUOUS`	Natural key resolves to multiple accounts	Pass `account_id` or more specific natural key
`ACCOUNT_PAYMENT_REQUIRED`	Credit limit reached or funds depleted	Add funds, route to another account
`ACCOUNT_SUSPENDED`	Account not in good standing	Contact seller
`BRAND_REQUIRED`	Billable operation without brand reference	Include `brand` in request

When the seller returns ACCOUNT_REQUIRED, it includes the available accounts:

{
  "errors": [{
    "code": "ACCOUNT_REQUIRED",
    "message": "Multiple accounts available. Please specify account_id in the account reference.",
    "details": {
      "available_accounts": [
        { "account_id": "acc_acme_001", "name": "Acme Corp" },
        { "account_id": "acc_pinnacle", "name": "Pinnacle Media" }
      ]
    }
  }]
}

Design notes

sync_accounts and seller record systems

When an agent declares (brand: {domain: "acme-corp.com"}, operator: "pinnacle-media.com"), the seller looks up or creates records in its own system — CRM, OMS, ad server, or billing platform. sync_accounts is the buyer-side interface to the seller’s record system. The seller may:

Map the natural key to an existing account and return status: "active"
Create a new record and return it immediately (status: "active")
Create a placeholder pending human review (status: "pending_approval")
Decline the request entirely (status: "rejected")

list_accounts returns all records the seller has mapped for this agent — including pending and rejected entries. The agent uses list_accounts to see the full state of its portfolio with this seller, not just active accounts.

Accounts and insertion orders

An account represents a standing relationship — who gets billed, what rates apply, what credit is available. It is not a campaign or an insertion order. Insertion orders and campaign flights are modeled as media buys via create_media_buy. The account determines billing terms; the media buy determines what runs and when. A single account can have many media buys over its lifetime.

Operator revocation and caching

If a brand removes an operator from authorized_operators, existing active accounts are not automatically deactivated. Revocation is eventual, not immediate — similar to how ads.txt changes propagate on the supply side. Sellers SHOULD respect standard HTTP caching headers on brand.json and re-validate periodically. A reasonable cache TTL is 24 hours.

Brand identity for SMBs

Domain-based identity via /.well-known/brand.json works for organizations of any size — it’s a static JSON file that can be hosted on any web server. For organizations that cannot host files on their domain, the authoritative_location field in brand.json allows the house domain to redirect to a hosted location:

{
  "house": {
    "domain": "local-bakery.com"
  },
  "authoritative_location": "https://registry.agenticadvertising.org/brands/local-bakery.com"
}

Getting Started

Building with AdCP

Protocol

Using AAO

FAQ

Trust & Security

Reference

Certification

Accounts and agents

What sellers declare

Seller patterns

Direct publisher

DSP / programmatic

Authorized operators

Verification flow

Buyer-agent identity

Account references

Account-id namespaces (`require_operator_auth: true`)

Buyer-declared accounts (`require_operator_auth: false`)

Billing entity and invoice recipient

Natural key semantics

Account status

Account scope

Seller walkthrough: buyer-declared accounts

1. Onboard the agent

2. Identify the caller on each request

3. Read the account operator from the request

4. Discover products with the natural key

5. Which error applies when

Error codes

Design notes

sync_accounts and seller record systems

Accounts and insertion orders

Operator revocation and caching

Brand identity for SMBs

​What sellers declare

​Seller patterns

​Social platform

​Direct publisher

​DSP / programmatic

​Authorized operators

​Verification flow

​Buyer-agent identity

​Account references

​Account-id namespaces (require_operator_auth: true)

​Buyer-declared accounts (require_operator_auth: false)

​Billing entity and invoice recipient

​Natural key semantics

​Account status

​Account scope

​Seller walkthrough: buyer-declared accounts

​1. Onboard the agent

​2. Identify the caller on each request

​3. Read the account operator from the request

​4. Discover products with the natural key

​5. Which error applies when

​Error codes

​Design notes

​sync_accounts and seller record systems

​Accounts and insertion orders

​Operator revocation and caching

​Brand identity for SMBs

What sellers declare

Seller patterns

Social platform

Direct publisher

DSP / programmatic

Authorized operators

Verification flow

Buyer-agent identity

Account references

Account-id namespaces (`require_operator_auth: true`)

Buyer-declared accounts (`require_operator_auth: false`)

Billing entity and invoice recipient

Natural key semantics

Account status

Account scope

Seller walkthrough: buyer-declared accounts

1. Onboard the agent

2. Identify the caller on each request

3. Read the account operator from the request

4. Discover products with the natural key

5. Which error applies when

Error codes

Design notes

sync_accounts and seller record systems

Accounts and insertion orders

Operator revocation and caching

Brand identity for SMBs