AdCP

Discover a seller’s protocol support and capabilities across all AdCP protocols. This is the first call a buyer should make to understand what a seller supports.

Why this shape. Capabilities are organized into ~14 top-level domain keys (one per protocol plus identity and signing infrastructure), with feature flags nested under each domain’s features/execution/etc. sub-namespace. We rejected a flat capability list — it forces every implementer to scan an unbounded surface, and it removes the discoverability that comes from related flags sitting next to each other. New capability flags belong under existing domains, not in new top-level keys; declarations are commitments, not advertisements (the conformance runner probes them). → Capabilities explorer walks the tree before you propose. → Design principle: capabilities are commitments.

Response Time: ~2 seconds (configuration lookup) Purpose:

AdCP discovery - Does this agent support AdCP? Which versions?
Protocol support - Which protocols (media_buy, signals, governance, sponsored_intelligence, creative, brand)?
Auth model - Does this seller trust the agent directly, or must each operator authenticate independently?
Detailed capabilities - Features, execution integrations, geo targeting, portfolio

Per-caller authorization is NOT reported here. get_adcp_capabilities returns the seller’s surface — everything it could do for any authorized caller. To discover what you are allowed to do on a specific account (which tasks are callable for your identity, which request fields are modifiable, any named scope like attestation_verifier), read the authorization object on per-account entries in sync_accounts and list_accounts responses. See Caller authorization for the full shape and semantics.

Request Schema: /schemas/v3/protocol/get-adcp-capabilities-request.json Response Schema: /schemas/v3/protocol/get-adcp-capabilities-response.json

Tool-Based Discovery

AdCP uses native MCP/A2A tool discovery. The presence of get_adcp_capabilities in an agent’s tool list indicates AdCP support.

Discovery Flow:
Browse agent's tool list (MCP) or skills (A2A)
See 'get_adcp_capabilities' tool → Agent supports AdCP
Call get_adcp_capabilities → Get version, protocols, features, capabilities
Proceed based on returned capabilities

This approach:

Uses standard MCP/A2A mechanisms (no custom extensions)
Always returns current capabilities (not stale metadata)
Single source of truth for all capability information

:::note The agent card extension (adcp-extension.json) has been removed in v3. Use tool-based discovery instead. :::

Version Negotiation

Sellers declare which major versions they support via adcp.major_versions in the response. Buyers declare which version they’re using via adcp_major_version on the request.

Version Negotiation Flow:
Buyer calls get_adcp_capabilities with adcp_major_version: 2
Seller checks 2 against its major_versions: [2, 3]
Version is supported → seller returns capabilities for v2
Buyer includes adcp_major_version: 2 on all subsequent requests

adcp_major_version is an optional field on every AdCP request schema. Buyers SHOULD include it on all requests when interacting with a multi-version seller. Seller behavior:

If adcp_major_version is provided and supported → respond using that version’s schemas
If adcp_major_version is provided but unsupported → return VERSION_UNSUPPORTED (buyer should call without adcp_major_version to discover supported versions)
If adcp_major_version is omitted → assume the highest supported version

Why major versions, not minor? Semver policy guarantees backward compatibility within a major version. A seller at 3.1 can serve a buyer at 3.0 without negotiation. The capability model handles feature-level differences — buyers check specific capabilities (targeting systems, features, extensions) rather than version numbers to determine compatibility.

Request Parameters

Field	Type	Description
`adcp_major_version`	integer	Optional. The AdCP major version the buyer’s payloads conform to. When provided, the seller validates against its `major_versions` and returns `VERSION_UNSUPPORTED` if not in range. When omitted, the seller assumes the highest major version it supports.
`protocols`	string[]	Optional. Filter to specific protocols (`media_buy`, `signals`, `governance`, `sponsored_intelligence`, `creative`, `brand`). If omitted, returns all supported protocols.

Response Structure

Core AdCP protocol information:

Field	Type	Description
`major_versions`	integer[]	Required. AdCP major versions supported (e.g., `[3]`)
`idempotency`	object	Required. Idempotency semantics. See idempotency.

idempotency

Declares whether this seller honors idempotency_key replay protection. From 3.1 onward idempotency_key is required on every AdCP task request (read and mutating alike — staged enforcement for reads: SHOULD-reject in 3.1, MUST-reject in 3.2; see security.mdx § Idempotency). Mirrors the request_signing.supported pattern — a single positive declaration, decoupled from the window detail. Clients MUST NOT assume a default; a seller without this block is non-compliant and should be treated as unsafe for retry-sensitive operations across all call modes.

Field	Type	Description
`supported`	boolean	Required. Whether the seller deduplicates replays. When `false`, sending an `idempotency_key` is a no-op — the seller will NOT return `IDEMPOTENCY_CONFLICT` or `IDEMPOTENCY_EXPIRED`, and a naive retry WILL double-process. Buyers MUST use natural-key checks (e.g., `get_media_buys` by `buyer_ref`) before retrying spend-committing operations.
`replay_ttl_seconds`	integer	Required when `supported: true`. How long the seller retains a canonical response for a key. Minimum `3600` (1h); recommended `86400` (24h); maximum `604800` (7d).

{
  "adcp": {
    "major_versions": [3],
    "idempotency": { "supported": true, "replay_ttl_seconds": 86400 }
  }
}

Sellers that do not support replay dedup declare it explicitly:

{
  "adcp": {
    "major_versions": [3],
    "idempotency": { "supported": false }
  }
}

Verifying the declaration. idempotency.supported: true is a trust-bearing claim that enables buyers to safely retry spend-committing operations. A compromised or buggy seller could advertise true while silently ignoring keys, causing buyer double-spend on retry. Buyers and conformance runners SHOULD probe the declaration with a deliberate payload-mutation replay: send two requests with the same idempotency_key but different canonical payloads — a conformant seller MUST return IDEMPOTENCY_CONFLICT on the second. Sellers declaring supported: true MUST pass this probe as part of the baseline compliance storyboard before the declaration is considered verified.

supported_protocols

AdCP protocols this agent supports. This is the single capability axis — each value both (a) declares which tools the agent implements and (b) commits the agent to pass the baseline compliance storyboard at /compliance/{version}/protocols/{protocol}/. The runner maps JSON snake_case → URL kebab-case (media_buy → /compliance/.../protocols/media-buy/).

{
  "supported_protocols": ["media_buy", "creative"]
}

Valid values: media_buy, creative, signals, governance, brand, sponsored_intelligence. See the Compliance Catalog for every protocol’s scope. Support for the compliance test controller is declared via the separate compliance_testing capability block (below), not as a protocol value.

specialisms

Optional specialization claims. Each entry corresponds to a narrow storyboard at /compliance/{version}/specialisms/{id}/. Every specialism rolls up to one protocol in supported_protocols — claiming sales-guaranteed requires media_buy. The runner rejects a specialism whose parent protocol is missing.

{
  "specialisms": ["sales-guaranteed", "creative-template"]
}

See the full Compliance Catalog for every specialism and the enum schema for the authoritative list.

account

Account and authentication capabilities. All sellers should declare this section — buyers read it before calling sync_accounts, list_accounts, or any authenticated task. Even simple publishers need account management to handle billing relationships and sandbox testing.

Field	Type	Description
`supported_billing`	string[]	Required. Billing models this seller supports: `operator`, `agent`. The buyer must pass one of these values as `billing` in every `sync_accounts` entry.
`require_operator_auth`	boolean	Default: `false`. Determines the account model. When `true` (explicit accounts): each operator authenticates independently, buyer discovers accounts via `list_accounts`, passes `account_id`. When `false` (implicit accounts): agent is trusted, buyer declares accounts via `sync_accounts`, passes natural key (`brand` + `operator`). For sandbox, the path follows the account model: explicit accounts discover pre-existing test accounts via `list_accounts`; implicit accounts declare sandbox via `sync_accounts` with `sandbox: true`.
`authorization_endpoint`	string	OAuth URL for operator authentication. Present when the seller supports OAuth for operator authentication. Relevant when `require_operator_auth: true`; if absent, operators obtain credentials out-of-band (seller portal, API key).
`required_for_products`	boolean	Default: `false`. When `true`, the buyer must establish an account before calling `get_products`. When `false`, the buyer can browse products without an account — useful for price comparison and discovery before committing to a seller.
`account_financials`	boolean	Default: `false`. When `true`, the seller supports `get_account_financials` for querying spend, credit, and invoice status. Only applicable to operator-billed accounts.
`sandbox`	boolean	Default: `false`. Strongly recommended for production sales agents. When `true`, the seller supports sandbox accounts for testing. For sandbox, the path follows the account model: explicit accounts discover pre-existing test accounts via `list_accounts`; implicit accounts declare sandbox via `sync_accounts` with `sandbox: true` — no real platform calls or spend. See Sandbox mode.

Auth models

Implicit accounts (require_operator_auth: false) — The seller trusts the agent’s identity claims. The agent authenticates once with its own bearer token, then calls sync_accounts to declare which brands and operators it represents. The seller provisions accounts based on the agent’s claims, optionally verifying operators against brand.json. All subsequent calls use the agent’s single credential and pass natural keys (brand + operator). Explicit accounts (require_operator_auth: true) — Each operator must authenticate with the seller directly. The agent obtains a credential per operator — via OAuth using authorization_endpoint, or out-of-band — opens a per-operator session, and discovers accounts via list_accounts. The buyer passes seller-assigned account_id values on all subsequent requests. For sandbox, the path follows the account model: explicit accounts (require_operator_auth: true) discover pre-existing test accounts via list_accounts; implicit accounts declare sandbox via sync_accounts with sandbox: true. See Accounts and Agents for full workflows and seller patterns for common combinations of auth model and billing support.

media_buy

Media-buy protocol capabilities. Only present if media_buy is in supported_protocols. Sellers declaring media_buy should also include account (with supported_billing) and media_buy.portfolio — buyers need both to establish billing and understand inventory coverage. Compliance testing validates their presence. :::note 3.0 breaking changes The following fields have been removed from the capabilities response:

media_buy.reporting — Reporting is implied by media_buy. Use product-level reporting_capabilities instead.
features.content_standards — Replaced by media_buy.content_standards object. Presence of the object indicates support.
features.audience_targeting — Replaced by media_buy.audience_targeting object. Presence of the object indicates support.
features.conversion_tracking — Replaced by media_buy.conversion_tracking object. Presence of the object indicates support.
execution.targeting.device_platform, device_type — Implied by media_buy support.
execution.targeting.audience_include, audience_exclude — Implied by audience_targeting object presence.
execution.trusted_match.supported — Object presence indicates support.
brand.identity — Implied by brand in supported_protocols. get_brand_identity is always available. :::

reporting_delivery_methods

Declares which push-based delivery methods are available across the seller’s product portfolio. Polling via get_media_buy_delivery is a required task for all media_buy sellers regardless of this field.

Method	Description	Configuration
`webhook`	Seller pushes to buyer-provided URL	Buyer configures `reporting_webhook` per media buy
`offline`	Seller pushes batch files to a cloud storage bucket	Seller provisions `reporting_bucket` per account

When absent, only polling is available. Cadence and metrics are declared per product in reporting_capabilities. When offline is declared, also include offline_delivery_protocols to declare which cloud storage protocols are supported (s3, gcs, azure_blob). Buyers express a protocol preference via preferred_reporting_protocol in sync_accounts; the seller provisions the account’s reporting_bucket using a supported protocol. For offline delivery, the seller provisions a per-account bucket and grants the buyer read access out-of-band. The bucket location (including file_retention_days) appears on the account object returned by sync_accounts as reporting_bucket. See Offline File Delivery for details.

features

Optional media-buy features. If declared true, seller MUST honor requests using that feature.

Feature	Description
`inline_creative_management`	Accepts creatives inline in `create_media_buy` requests
`property_list_filtering`	Honors `property_list` parameter in `get_products`
`catalog_management`	Supports `sync_catalogs` for catalog feed management

content_standards

Content standards implementation details. Presence of this object indicates the seller supports content_standards configuration including sampling rates and category filtering. Gives buyers pre-buy visibility into local evaluation and artifact delivery capabilities.

Field	Type	Description
`supports_local_evaluation`	boolean	Whether the seller runs a local evaluation model. When `false`, `local_verdict` will always be `unevaluated` and the `failures_only` filter on `get_media_buy_artifacts` is not useful.
`supported_channels`	string[]	Channels for which the seller can provide content artifacts. Helps buyers understand which parts of a mixed-channel buy will have content standards coverage.
`supports_webhook_delivery`	boolean	Whether the seller supports push-based artifact delivery via `artifact_webhook` configured at buy creation time.

Example:

{
  "content_standards": {
    "supports_local_evaluation": true,
    "supported_channels": ["display", "olv", "podcast"],
    "supports_webhook_delivery": true
  }
}

If supports_local_evaluation is false, the failures_only filter on get_media_buy_artifacts will return an empty result set — all verdicts will be unevaluated.

execution

Technical execution capabilities:

Field	Type	Description
`trusted_match`	object	TMP support. When present, this seller supports real-time contextual and/or identity matching. Check individual products for per-product TMP capabilities.
`axe_integrations`	string[]	Deprecated. Legacy AXE URLs this seller can execute through. Use `trusted_match` for new integrations.
`creative_specs`	object	Creative specification support (VAST versions, MRAID, etc.)
`targeting`	object	Targeting capabilities (geo granularity)

axe_integrations

axe_integrations is an array of Agentic Ad Exchange (AXE) endpoint URLs that this seller can execute through. AXE is the real-time execution layer for AdCP campaigns — it connects buyer agents to programmatic inventory via standardized exchanges. When a seller declares AXE URLs in their capabilities, buyers can:

Route impression-level execution through the declared exchange
Use the exchange’s targeting, optimization, and measurement capabilities
Execute alongside the seller’s direct-sold inventory

Buyers discover AXE support via get_adcp_capabilities and filter products to AXE-enabled sellers using required_axe_integrations on get_products.

creative_specs

Field	Type	Description
`vast_versions`	string[]	VAST versions supported (e.g., `["4.0", "4.1", "4.2"]`)
`mraid_versions`	string[]	MRAID versions supported
`vpaid`	boolean	VPAID support
`simid`	boolean	SIMID support

targeting

Field	Type	Description
`geo_countries`	boolean	Country-level targeting using ISO 3166-1 alpha-2 codes
`geo_regions`	boolean	Region/state-level targeting using ISO 3166-2 codes (e.g., `US-NY`, `GB-SCT`)
`geo_metros`	object	Metro area targeting with system-specific support
`geo_postal_areas`	object	Postal area targeting with country and precision support
`age_restriction`	object	Age restriction capabilities with `supported` flag and `verification_methods`
`language`	boolean	Language targeting (ISO 639-1 codes)
`keyword_targets`	object	Keyword targeting with `supported_match_types` array (`broad`, `phrase`, `exact`). Presence indicates support.
`negative_keywords`	object	Negative keyword targeting with `supported_match_types` array. Presence indicates support.
`geo_proximity`	object	Proximity targeting from arbitrary coordinates (see below)

Device platform and device type targeting are implied by media_buy support. Audience include/exclude targeting is implied by the presence of the audience_targeting capabilities object. Sellers that support a geographic targeting level SHOULD support both inclusion and exclusion at that level. For example, geo_metros.nielsen_dma: true SHOULD mean the seller supports both geo_metros and geo_metros_exclude with Nielsen DMA codes. If a seller only supports one direction (e.g., inclusion but not exclusion), it MUST return a validation error for unsupported fields rather than silently ignoring them. See Targeting Overlays for exclusion semantics. geo_proximity specifies which proximity targeting methods are supported:

Field	Type	Description
`radius`	boolean	Simple radius targeting (distance circle from a point)
`travel_time`	boolean	Travel time isochrone targeting (requires a routing engine)
`geometry`	boolean	Pre-computed GeoJSON geometry (buyer provides the polygon)
`transport_modes`	string[]	Transport modes supported for isochrones: `driving`, `walking`, `cycling`, `public_transport`

geo_metros specifies which metro classification systems are supported:

System	Description
`nielsen_dma`	Nielsen DMA codes (US market, e.g., `501` for NYC)
`uk_itl1`	UK ITL Level 1 regions
`uk_itl2`	UK ITL Level 2 regions
`eurostat_nuts2`	Eurostat NUTS Level 2 regions (EU)

geo_postal_areas specifies which postal code systems are supported:

System	Description
`us_zip`	US 5-digit ZIP codes (e.g., `10001`)
`us_zip_plus_four`	US 9-digit ZIP+4 codes (e.g., `10001-1234`)
`gb_outward`	UK postcode district (e.g., `SW1`, `EC1`)
`gb_full`	UK full postcode (e.g., `SW1A 1AA`)
`ca_fsa`	Canadian Forward Sortation Area (e.g., `K1A`)
`ca_full`	Canadian full postal code (e.g., `K1A 0B1`)
`de_plz`	German Postleitzahl (e.g., `10115`)
`fr_code_postal`	French code postal (e.g., `75001`)
`au_postcode`	Australian postcode (e.g., `2000`)
`ch_plz`	Swiss Postleitzahl (e.g., `8000`)
`at_plz`	Austrian Postleitzahl (e.g., `1010`)

audience_targeting

Audience targeting capabilities. Presence of this object indicates the seller supports audience targeting, including sync_audiences and audience_include/audience_exclude in targeting overlays. Describes what identifier types the seller accepts for audience matching, size constraints, and expected matching latency.

Field	Type	Required	Description
`supported_identifier_types`	string[]	Required	PII-derived identifier types accepted for audience matching. Buyers should only send identifiers the seller supports. Values: `hashed_email`, `hashed_phone`.
`minimum_audience_size`	integer	Required	Minimum matched audience size required for targeting. Audiences below this threshold will have `status: too_small`. Varies by platform (100–1000 is typical).
`supports_platform_customer_id`	boolean		When `true`, the seller accepts the buyer’s CRM/loyalty ID as a matchable identifier. Only applicable when the seller operates a closed ecosystem with a shared ID namespace (e.g., a retailer matching against their loyalty program). Buyers can include `platform_customer_id` values in `AudienceMember.identifiers`. Reporting on matched IDs typically requires a clean room or the seller’s own reporting surface.
`supported_uid_types`	string[]		Universal ID types accepted for audience matching (MAIDs, RampID, UID2, etc.). MAID support varies significantly by platform — check this field before sending `uids` with `type: maid`.
`matching_latency_hours`	object		Expected matching latency range in hours after upload. Use to calibrate polling cadence and set appropriate expectations before configuring `push_notification_config`. Shape: `{ min: integer, max: integer }`.

conversion_tracking

Seller-level conversion tracking capabilities. Declares what the seller supports for kind: "event" optimization goals.

Field	Type	Description
`multi_source_event_dedup`	boolean	Whether the seller can deduplicate events across multiple event sources within a single goal. When `true`, the same `event_id` from multiple sources counts once. When `false` or absent, buyers should use a single event source per goal.
`supported_event_types`	string[]	Event types this seller can track. If omitted, all standard event types are supported.
`supported_uid_types`	string[]	Universal ID types accepted for user matching.
`supported_hashed_identifiers`	string[]	Hashed PII types accepted (`hashed_email`, `hashed_phone`). Buyers must hash before sending (SHA-256, normalized).
`supported_action_sources`	string[]	Action sources this seller accepts events from.
`attribution_windows`	object[]	Available attribution windows. Single-element arrays indicate fixed windows; multi-element arrays indicate configurable options the buyer can choose from via `attribution_window` on optimization goals.

portfolio

Inventory portfolio information:

Field	Type	Description
`publisher_domains`	string[]	Required. Publisher domains this seller represents
`primary_channels`	string[]	Main advertising channels
`primary_countries`	string[]	Main countries (ISO codes)
`description`	string	Markdown portfolio description
`advertising_policies`	string	Content policies and restrictions

signals

Signals protocol capabilities. Only present if signals is in supported_protocols.

Field	Type	Description
`data_provider_domains`	string[]	Data provider domains this signals agent is authorized to resell. Buyers should fetch each provider’s `adagents.json` for signal catalog definitions and to verify authorization.
`discovery_modes`	string[]	Discovery modes the agent supports on `get_signals`. `"brief"` (semantic discovery via `signal_spec` / `signal_ids`) is implicit and always supported. Declare `"wholesale"` to advertise that callers can omit `signal_spec` / `signal_ids` and enumerate the full priced signals feed. Agents not declaring `"wholesale"` MAY return `INVALID_REQUEST` for wholesale calls. Absent declaration is treated as `["brief"]`.
`features.catalog_signals`	boolean	Supports signals from data provider catalogs with structured `signal_id` references.

creative

Creative protocol capabilities. Only present if creative is in supported_protocols.

Field	Type	Description
`supports_compliance`	boolean	When `true`, this creative agent can process briefs with compliance requirements (`required_disclosures`, `prohibited_claims`) and will validate that disclosures can be satisfied by the target format. Use the `disclosure_positions` filter on `list_creative_formats` to find compatible formats.
`bills_through_adcp`	boolean	When `true`, this creative agent bills through the AdCP rate-card surface — `list_creatives` returns `pricing_options` (with `include_pricing=true` and an authenticated account), `build_creative` populates `pricing_option_id` and `vendor_cost`, and `report_usage` accepts records against the rate card. When `false` or absent, the agent bills out of band (flat license, SaaS contract, bundled enterprise agreement); buyers should skip pricing fields and tolerate `report_usage` returning `accepted: 0` with `BILLING_OUT_OF_BAND` errors. Pre-call discriminator for routing across creative agents.

governance

Governance protocol capabilities. Only present if governance is in supported_protocols. Governance agents declare capabilities across four domains: property evaluation, creative evaluation, content standards verification, and policy registry integration.

property_features

Array of property features this governance agent can evaluate. See Property Governance.

Field	Type	Description
`feature_id`	string	Required. Unique identifier (e.g., `mfa_score`, `coppa_certified`). Use `registry:{policy_id}` prefix for features mapped to Policy Registry entries.
`type`	string	Required. Data type: `binary`, `quantitative`, or `categorical`
`range`	object	For quantitative: `{ min, max }`
`categories`	string[]	For categorical: valid values
`description`	string	Human-readable description
`methodology_url`	string	URL to methodology documentation

creative_features

Array of creative features this governance agent can evaluate. Same field schema as property_features. See Creative Governance. Creative governance agents evaluate creatives for security, content categorization, and regulatory compliance. Buyers filter creatives by feature requirements — for example, blocking creatives flagged for auto_redirect or requiring registry:eu_ai_act_article_50 compliance.

content_standards

Content standards verification capabilities. See Content Standards.

Field	Type	Description
`supported`	boolean	Whether this agent can serve as a content standards verification agent
`calibration_formats`	string[]	Artifact asset types this agent can evaluate (e.g., `text`, `image`, `video`, `audio`)

policy_registry

Policy registry integration capabilities. See Policy Registry.

Field	Type	Description
`supported`	boolean	Whether this agent consumes policies from the AdCP Policy Registry
`domains`	string[]	Governance domains this agent covers (e.g., `campaign`, `property`, `creative`, `content_standards`)

Example governance agent response:

{
  "$schema": "/schemas/protocol/get-adcp-capabilities-response.json",
  "status": "completed",
  "adcp": {
    "major_versions": [3],
    "idempotency": { "supported": true, "replay_ttl_seconds": 86400 }
  },
  "supported_protocols": ["governance"],
  "governance": {
    "property_features": [
      { "feature_id": "mfa_score", "type": "quantitative", "range": { "min": 0, "max": 100 }, "description": "Made For Advertising detection (0=quality content, 100=likely MFA)", "methodology_url": "https://vendor.example.com/methodology/mfa" },
      { "feature_id": "coppa_certified", "type": "binary", "description": "COPPA compliance certification" },
      { "feature_id": "registry:uk_hfss", "type": "binary", "description": "UK HFSS advertising restrictions compliance" },
      { "feature_id": "carbon_score", "type": "quantitative", "range": { "min": 0, "max": 100 }, "description": "Carbon footprint sustainability score", "methodology_url": "https://vendor.example.com/methodology/carbon-score" }
    ],
    "creative_features": [
      { "feature_id": "registry:eu_ai_act_article_50", "type": "binary", "description": "EU AI Act Article 50 — AI-generated content disclosure" },
      { "feature_id": "registry:ca_sb_942", "type": "binary", "description": "California SB 942 — AI transparency compliance" },
      { "feature_id": "auto_redirect", "type": "binary", "description": "Detects auto-redirect behavior in creative code" },
      { "feature_id": "credential_harvest", "type": "binary", "description": "Detects credential harvesting patterns" }
    ],
    "content_standards": {
      "supported": true,
      "calibration_formats": ["text", "image", "video"]
    },
    "policy_registry": {
      "supported": true,
      "domains": ["campaign", "property", "creative", "content_standards"]
    }
  }
}

measurement

Measurement protocol capabilities. Only present if measurement is in supported_protocols. The measurement protocol is in development — currently scoped to get_adcp_capabilities for catalog discovery (this block); additional measurement tasks (reporting, attribution, panel queries) and a baseline compliance storyboard land in subsequent minors. The capability block is shipping now so measurement vendors can publish their per-metric catalogs and AAO can crawl them, before the broader task surface is settled. Scope. An agent claiming measurement computes one or more quantitative metrics about ad delivery, exposure, or effect (impression verification, viewability, IVT, attention, brand lift, incrementality, outcomes, emissions — vendors define the surface in metrics[]). Returns metric definitions (this block), not pricing or coverage (negotiated per buy via measurement_terms) and not live values (returned per buy via vendor_metric_values). Same mechanical model as compliance_testing and webhook_signing: presence asserts the capability; the block carries the structured payload. Measurement agents publish a per-metric catalog so buyers know which metrics each vendor offers. This is the canonical source of truth — AAO crawls it to populate the federated measurement-vendor index.

metrics

Array of metrics this measurement agent computes.

Field	Type	Description
`metric_id`	string	Required. Vendor-scoped identifier (`attention_units`, `gco2e_per_impression`, etc.) — matches the `metric_id` populated in `vendor_metric_values` on delivery. The full identity is the tuple `(vendor.domain, vendor.brand_id, metric_id)`. Each `metric_id` MUST be unique within a single agent’s catalog.
`standard_reference`	string (URI)	Optional URI pointing at the published standard this metric implements (IAB Attention Measurement Guidelines, MRC Viewable Impression Measurement, GARM emissions framework). Distinct from `accreditations` below — `standard_reference` is what the metric is built against; `accreditations` is third-party certification of conformance.
`accreditations`	object[]	Optional list of third-party accreditations this metric holds (MRC, ARF, JIC bodies, ABC, BARB, AGOF, etc.). Each entry: `accrediting_body` (required), optional `certification_id`, `valid_until`, `evidence_url`. Buyers asking “is this MRC-accredited?” SHOULD check this array — implementing a standard is not the same as being independently accredited.
`unit`	string	Unit of the value when reported in `vendor_metric_values.value` (`score`, `seconds`, `persons`, `gCO2e`, `lift_percent`, `USD`, etc.). Sellers populating `vendor_metric_values.unit` MUST match this declaration.
`description`	string	Human-readable description of what the metric measures and any methodology notes. AAO and buyer agents normalize across catalogs from this field plus the structured fields above; classification facets are not declared at the metric level.
`methodology_url`	string (URI)	URL to vendor’s full methodology documentation. Mirrors `governance.property_features[].methodology_url`.
`methodology_version`	string	Optional version identifier (semver, ISO date, or vendor-defined string) for the methodology. When present, buyer agents can pin a contracted version so silent methodology changes are detectable; absence means the vendor does not version their methodology and buyers MUST treat any change as untracked.
`ext`	object	Vendor extensions per the AdCP `ext` convention.

Response example

{
  "measurement": {
    "metrics": [
      {
        "metric_id": "attention_units",
        "standard_reference": "https://iabtechlab.com/standards/attention-measurement",
        "accreditations": [
          { "accrediting_body": "MRC", "certification_id": "MRC-ATT-2026-001", "valid_until": "2027-12-31", "evidence_url": "https://mediaratingcouncil.org/accreditations/attentionvendor" }
        ],
        "unit": "score",
        "description": "Eye-tracking-based attention score (0-100). Computed from a panel of 25K opted-in households.",
        "methodology_url": "https://attentionvendor.example/docs/attention-units",
        "methodology_version": "v2.1"
      },
      {
        "metric_id": "engagement_seconds",
        "unit": "seconds",
        "description": "Active dwell time in seconds, measured via in-content telemetry."
      }
    ]
  }
}

Discovery vs. settlement. Buyers MAY hit a measurement agent’s get_adcp_capabilities directly to see its current catalog (live, canonical, no staleness), or query AAO’s federated index for cross-vendor aggregation. The index trades a TTL refresh window for cross-vendor speed; live calls trade speed for currency. Both are valid — typically planning queries hit the index, settlement/audit queries hit the agent. This is a discovery surface, not a rate card. The catalog tells buyers what a vendor measures and what standards/accreditations back it. Pricing per impression, minimum measurable inventory, attribution windows, geographic coverage, and data-freshness SLAs are negotiated per buy through the seller’s measurement_terms on create_media_buy — not through this catalog.

compliance_testing

Compliance testing capabilities. The presence of this block declares that the agent supports deterministic testing via comply_test_controller. Omit the block if the agent does not support compliance testing. Production deployments MUST NOT include this block. comply_test_controller is sandbox-only at the deployment level; advertising the capability on a production endpoint is non-conformant even if dispatch is gated. See Compliance test controller § Sandbox gating.

Field	Type	Description
`scenarios`	string[]	Compliance testing scenarios this agent supports. Possible values: `force_creative_status`, `force_account_status`, `force_media_buy_status`, `force_session_status`, `simulate_delivery`, `simulate_budget_spend`, `seed_product`, `seed_pricing_option`, `seed_creative`, `seed_plan`, `seed_media_buy`. Runners MUST accept unknown scenario strings — new scenarios may be added in additive minor bumps.

Storyboard runners check for the compliance_testing block before running deterministic testing steps. If the agent does not include the block, controller-dependent storyboard steps cannot be validated. Agents that implement comply_test_controller SHOULD include the compliance_testing capability block and list supported scenarios. Agents that only support a subset of scenarios (e.g., media buy status but not SI sessions) declare only those scenarios — the runner skips unsupported ones. :::note Compliance testing is sandbox-only at the deployment level — production deployments MUST NOT advertise this block or expose comply_test_controller on any surface. FORBIDDEN is returned only when an in-sandbox caller passes params that reference a non-sandbox account; live-mode probes for the tool by name receive the transport’s standard unknown-tool error. See Sandbox gating. :::

webhook_signing

Declares a seller’s webhook-signing posture. Any seller whose capability surface advertises mutating-webhook emission — including but not limited to media_buy.reporting_delivery_methods containing webhook, media_buy.content_standards.supports_webhook_delivery: true, or wholesale_feed_webhooks.supported: true — MUST include this block with supported: true. A seller that emits no webhooks at all MAY omit the block entirely; the absence of both mutating-webhook emission in other capabilities and this block is an unambiguous “does not emit webhooks” posture. Buyers read the block at onboarding to determine which algorithms to expect per the AdCP webhook-signing profile. Buyers integrating with a seller that advertises mutating-webhook emission while advertising supported: false or omitting this block MUST fail onboarding with a user-actionable error; silent integration with a non-signing-but-webhook-emitting seller is unsafe for any mutating-webhook use case.

Field	Type	Description
`supported`	boolean	Required when the seller advertises mutating-webhook emission elsewhere in its capability surface. `true` iff the seller signs outbound webhooks. `false` means the seller emits webhooks but does not sign them; buyers MUST fail onboarding. Sellers that emit no webhooks SHOULD omit the entire block rather than set `supported: false` — `false` is reserved for the unsafe posture of unsigned-webhook emission, not absence-of-webhooks.
`profile`	string	Required when `supported: true`. The profile version string. Currently `"adcp/webhook-signing/v1"`. Future versions bump the string.
`algorithms`	string[]	Required when `supported: true`. Subset of `["ed25519", "ecdsa-p256-sha256"]` — the algorithms this seller will sign webhooks with. Matches the webhook-signing verifier allowlist (see Verifier checklist for webhooks, step 4). Buyers MUST be prepared to verify any algorithm listed AND MUST reject onboarding with a user-actionable error if an advertised algorithm is outside this enumerated set — a seller advertising an out-of-set algorithm (e.g., `hs256`) is either misconfigured or signalling a non-conforming profile.
`legacy_hmac_fallback`	boolean	Required when `supported: true`. `true` iff the seller supports the legacy HMAC-SHA256 scheme when the buyer populates `push_notification_config.authentication.credentials` or `accounts[].notification_configs[].authentication.credentials`. `false` is the recommended posture in 3.x — the HMAC scheme is removed in AdCP 4.0.

Example:

{
  "webhook_signing": {
    "supported": true,
    "profile": "adcp/webhook-signing/v1",
    "algorithms": ["ed25519", "ecdsa-p256-sha256"],
    "legacy_hmac_fallback": false
  }
}

The webhook-signing block is parallel to request_signing (inbound) and the two blocks cover the two signing directions between buyer and seller. Buyers SHOULD validate both at onboarding; a seller that signs one direction but not the other has a lopsided security posture that operators need to notice explicitly.

extensions_supported

Array of extension namespaces this agent supports. Buyers can expect meaningful data in ext.{namespace} fields on responses from this agent.

Field	Type	Description
`extensions_supported`	string[]	Extension namespaces (e.g., `["iab_tcf", "iab_gpp"]`)

Extension schemas are published in the AdCP extension registry. When an agent declares support for an extension, buyers know to look for and process ext.{namespace} data in responses. Example:

{
  "extensions_supported": ["iab_tcf", "iab_gpp", "acmecorp"]
}

This tells buyers:

Responses may include ext.iab_tcf with IAB TCF consent data
Responses may include ext.iab_gpp with IAB GPP (Global Privacy Platform) signals
Responses may include ext.acmecorp with vendor-specific data from Acme Corp

experimental_features

Array of experimental AdCP surfaces this agent implements. A surface is experimental when its schema carries x-status: experimental — it is part of the core protocol but not yet frozen and may break between 3.x releases with 6 weeks’ notice. Sellers that implement any experimental surface MUST list its feature id here.

Field	Type	Description
`experimental_features`	string[]	Experimental feature ids (e.g., `["brand.rights_lifecycle", "governance.campaign", "trusted_match.core", "sponsored_intelligence.core"]`)

Buyers should inspect experimental_features before relying on an experimental surface. A seller that does not list a surface is asserting it does not implement it — there is no “silently experimental” mode. Example:

{
  "experimental_features": ["brand.rights_lifecycle", "trusted_match.core"]
}

See experimental status for the full stability contract, graduation criteria, and client guidance.

wholesale_feed_versioning

Conditional-fetch token capabilities for get_products and get_signals. Independent of wholesale feed webhooks: an agent MAY support cheap version probes without pushing change payloads, and an agent MAY push change payloads while still requiring reconciliation reads for repair.

Field	Type	Description
`supported`	boolean	Required. Whether the agent returns `wholesale_feed_version` on responses and honors `if_wholesale_feed_version` on requests. When absent or `false`, buyers can still probe by reading the response (the field-presence detection path) but can’t pre-flight-decide which agents to cache versions for.
`pricing_version_separate`	boolean	Whether the agent tracks `pricing_version` independently of `wholesale_feed_version`. When `true`, callers can send `if_pricing_version` alongside `if_wholesale_feed_version` for finer-grained “did prices change?” probes. When `false` or absent, the agent collapses both into `wholesale_feed_version` — sending `if_pricing_version` is wasted bytes.
`cache_scope_account`	boolean	Whether the agent ever returns `cache_scope: "account"` (i.e., publishes per-account overlays distinct from the public rate card). When `true`, buyers MUST be prepared to maintain account-overlay caches alongside the public layer. When `false` or absent, all responses are `cache_scope: "public"` — the agent’s rate card is universal across accounts. Note: declaring `true` advertises that the agent runs custom-pricing deals, which is itself a small market-posture signal; agents preferring confidentiality MAY omit the field and detect-on-call instead.

Example:

{
  "wholesale_feed_versioning": {
    "supported": true,
    "pricing_version_separate": true,
    "cache_scope_account": true
  }
}

wholesale_feed_webhooks

Per-agent wholesale product-feed and wholesale signals-feed webhook capabilities. Declared by sales agents (products) and signals agents (signals). When supported is true, consumers can register sync_accounts.accounts[].notification_configs[] entries for product.*, signal.*, and wholesale_feed.bulk_change events and receive the actual change payload in each webhook. See specs/wholesale-feed-webhooks.md for the full spec. Terminology. Here “wholesale feed” means the agent’s buyable wholesale product feed and wholesale signals feed exposed by get_products and get_signals. It is distinct from sync_catalogs, which pushes buyer-provided campaign input feeds into a seller account for campaign execution. Complementary to (and independent of) wholesale_feed_versioning: webhooks push changed products/signals or bulk-change summaries; version tokens give a cheap repair and reconciliation probe. Adopters MAY ship either, both, or neither. Agents that declare supported: true MUST apply the same account/caller authorization and scope predicate used by the corresponding wholesale read before emitting each webhook. A caller that could not see a product, signal, price, or account overlay through get_products buying_mode: "wholesale" or get_signals discovery_mode: "wholesale" MUST NOT receive a webhook revealing that change. Agents unable to guarantee per-principal filtering MUST NOT declare support. Capability consistency. Agents listing any product.* value in event_types[] MUST declare and support wholesale get_products (media_buy.buying_modes includes "wholesale"). Agents listing any signal.* value MUST declare and support wholesale get_signals (signals.discovery_modes includes "wholesale"). Agents listing wholesale_feed.bulk_change MUST have at least one of those wholesale repair paths, and each bulk-change payload’s affected_entity_type MUST name only a feed family the agent can repair through a declared wholesale read. Consumer precedence. When more than one mechanism is declared, consumers SHOULD prefer them in this order: (1) wholesale_feed_webhooks when maintaining a long-lived mirror (lowest latency, lowest seller cost); (2) wholesale_feed_versioning conditional fetch for occasional polling and webhook repair; (3) wholesale enumeration via buying_modes / discovery_modes for cold start, wholesale_feed.bulk_change, or any missed/distrusted push.

Field	Type	Description
`supported`	boolean	Required. Whether this agent can push wholesale feed change payloads through account-level `sync_accounts.accounts[].notification_configs[]`. When `false` or this stanza is absent, consumers fall back to wholesale polling, optionally with `if_wholesale_feed_version` probes.
`event_types`	string[]	Event types this agent can emit. Sales agents emit `product.` events; signals agents emit `signal.` events; agents that are both can emit both event families. `product.` requires wholesale `get_products`; `signal.` requires wholesale `get_signals`; `wholesale_feed.bulk_change` requires at least one declared wholesale repair path and names one affected feed the consumer repairs by re-reading via `get_products` or `get_signals`.

Example (sales + signals agent):

{
  "wholesale_feed_webhooks": {
    "supported": true,
    "event_types": [
      "product.created", "product.updated", "product.priced", "product.removed",
      "signal.created", "signal.updated", "signal.priced", "signal.removed",
      "wholesale_feed.bulk_change"
    ]
  }
}

The Capability Contract

If a capability is declared, the seller MUST honor it.

media_buy.execution.targeting.geo_postal_areas.us_zip: true → Buyer can send US ZIP codes, seller MUST honor them
media_buy.execution.targeting.geo_metros.nielsen_dma: true → Buyer can send DMA codes, seller MUST honor them
media_buy.content_standards object present → Seller MUST apply content standards when provided
media_buy.audience_targeting object present → Seller MUST support sync_audiences and audience targeting overlays
media_buy.conversion_tracking object present → Seller MUST support sync_event_sources and log_event
AXE URL in media_buy.execution.axe_integrations → Seller can execute through that exchange (legacy — new integrations use TMP)

No silent ignoring. If a seller can’t support a capability, they should declare false or omit it.

Common Scenarios

Basic Capability Discovery

import { AdcpClient } from '@adcp/sdk';

const client = new AdcpClient({ baseUrl: 'https://seller.example.com/mcp' });

// Get seller capabilities
const result = await client.getAdcpCapabilities({});

if (result.errors) {
  throw new Error(`Request failed: ${result.errors[0].message}`);
}

// Check protocol support
console.log(`AdCP versions: ${result.adcp.major_versions.join(', ')}`);
console.log(`Supported protocols: ${result.supported_protocols.join(', ')}`);

// Check media-buy capabilities
if (result.supported_protocols.includes('media_buy')) {
  const mediaBuy = result.media_buy;

  // Check content standards support (object presence = signal)
  if (mediaBuy.content_standards) {
    console.log('Content standards supported');
  }

  // Check AXE integrations (legacy — new integrations use TMP via trusted_match on products)
  if (mediaBuy.execution?.axe_integrations?.includes('https://axe.example.com')) {
    console.log('AXE integration available');
  }

  // Check geo targeting
  if (mediaBuy.execution?.targeting?.geo_postal_areas?.us_zip) {
    console.log('US ZIP code targeting supported');
  }

  // Portfolio overview
  console.log(`Publishers: ${mediaBuy.portfolio.publisher_domains.length}`);
  console.log(`Channels: ${mediaBuy.portfolio.primary_channels?.join(', ')}`);
}

Check multi-protocol support

const caps = await client.getAdcpCapabilities({});

const sellsMedia = caps.supported_protocols.includes('media_buy');
const managesCreatives = caps.supported_protocols.includes('creative');

if (sellsMedia && managesCreatives) {
  // Single agent handles both protocols — no need to discover a separate service
  const formats = await client.listCreativeFormats({});
  const delivery = await client.getCreativeDelivery({
    media_buy_ids: ['mb_12345']
  });
}

Filter sellers by capability

// Find sellers that support specific requirements
async function findCompatibleSellers(sellers, requirements) {
  const compatible = [];

  for (const sellerUrl of sellers) {
    const client = new AdcpClient({ baseUrl: sellerUrl });
    const caps = await client.getAdcpCapabilities({});

    if (caps.errors) continue;

    // Must support media_buy protocol
    if (!caps.supported_protocols.includes('media_buy')) continue;

    const mediaBuy = caps.media_buy;

    // Check AXE integration requirement (legacy — new integrations use TMP)
    if (requirements.axeIntegration) {
      if (!mediaBuy.execution?.axe_integrations?.includes(requirements.axeIntegration)) {
        continue;
      }
    }

    // Check geo targeting requirement
    if (requirements.postalCodeTargeting) {
      if (!mediaBuy.execution?.targeting?.geo_postal_areas?.us_zip) {
        continue;
      }
    }

    // Check content standards requirement (object presence = signal)
    if (requirements.contentStandards) {
      if (!mediaBuy.content_standards) {
        continue;
      }
    }

    compatible.push({ url: sellerUrl, capabilities: caps });
  }

  return compatible;
}

// Usage
const sellers = await findCompatibleSellers(
  ['https://seller1.com/mcp', 'https://seller2.com/mcp'],
  {
    axeIntegration: 'https://axe.example.com',
    postalCodeTargeting: true,
    contentStandards: true
  }
);

Use Capabilities to Build Targeting

Capabilities tell you what you CAN specify in create_media_buy targeting. Use required_geo_targeting to filter products to sellers that support specific geo targeting levels and systems:

// First, check capabilities
const caps = await client.getAdcpCapabilities({});

if (!caps.supported_protocols.includes('media_buy')) {
  throw new Error('Seller does not support media_buy protocol');
}

const mediaBuy = caps.media_buy;

// Filter products to sellers with specific geo targeting capabilities
const products = await client.getProducts({
  brief: "Premium video inventory in US for ZIP-targeted campaign",
  filters: {
    channels: ['olv', 'ctv'],
    countries: ['US'],
    // Require seller supports ZIP targeting (capability filter - no actual ZIPs needed)
    // level = granularity, system = classification taxonomy
    required_geo_targeting: [
      { level: 'postal_area', system: 'us_zip' }
    ],
    // Only include if seller supports this AXE (legacy — new integrations use TMP)
    required_axe_integrations: ['https://axe.example.com']
  }
});

// Then, create media buy with fine-grained targeting
// (if seller supports postal areas, we can target specific ZIP codes)
const buy = await client.createMediaBuy({
  brand: { domain: 'mybrand.com' },
  packages: [{
    product_id: products.products[0].product_id,
    pricing_option_id: products.products[0].pricing_options[0].id,
    budget: 10000,
    // Targeting overlay refines delivery within product coverage
    targeting_overlay: {
      geo_countries: ['US'],
      // Only specify ZIP targeting if seller supports it
      ...(mediaBuy.execution?.targeting?.geo_postal_areas?.us_zip && {
        geo_postal_areas: [{
          system: 'us_zip',
          values: ['10001', '10002', '10003', '10004', '10005']
        }]
      })
    }
  }],
  start_time: { type: 'asap' },
  end_time: '2025-03-01T00:00:00Z'
});

Two models for product geography:

Inventory Type	Filter By	Example
Digital (display, OLV, CTV)	Capability: `required_geo_targeting`	Products have broad coverage, target at buy time
Local (radio, DOOH, local TV)	Coverage: `metros`, `regions`	Products ARE geographically bound

Digital inventory: Use countries + required_geo_targeting (capability), apply fine-grained targeting in create_media_buy
Local inventory: Use metros/regions (coverage) to find products with coverage in your target markets

Local Inventory Example (Radio, DOOH)

For locally-bound inventory, products ARE geographically specific. A radio station in NYC DMA only covers NYC.

// Find radio products in specific DMAs
const radioProducts = await client.getProducts({
  brief: "Radio inventory in NYC and LA markets",
  filters: {
    channels: ['radio'],
    // Coverage filter: products must cover these metros
    metros: [
      { system: 'nielsen_dma', code: '501' },  // NYC
      { system: 'nielsen_dma', code: '803' }   // LA
    ]
  }
});

// For local inventory, targeting_overlay is optional -
// the product's coverage IS the geography
const buy = await client.createMediaBuy({
  brand: { domain: 'mybrand.com' },
  packages: [{
    product_id: radioProducts.products[0].product_id,
    pricing_option_id: radioProducts.products[0].pricing_options[0].id,
    budget: 5000
    // No targeting_overlay needed - product covers NYC DMA
  }],
  start_time: { type: 'asap' },
  end_time: '2025-03-01T00:00:00Z'
});

Response Example

{
  "$schema": "/schemas/protocol/get-adcp-capabilities-response.json",
  "status": "completed",
  "adcp": {
    "major_versions": [3],
    "idempotency": { "supported": true, "replay_ttl_seconds": 86400 }
  },
  "supported_protocols": ["media_buy"],
  "account": {
    "require_operator_auth": false,
    "supported_billing": ["operator", "agent"]
  },
  "media_buy": {
    "features": {
      "inline_creative_management": true,
      "property_list_filtering": true
    },
    "execution": {
      "axe_integrations": ["https://axe.example.com"],
      "creative_specs": {
        "vast_versions": ["4.0", "4.1", "4.2"],
        "mraid_versions": ["3.0"],
        "vpaid": false,
        "simid": true
      },
      "targeting": {
        "geo_countries": true,
        "geo_regions": true,
        "geo_metros": {
          "nielsen_dma": true
        },
        "geo_postal_areas": {
          "us_zip": true,
          "gb_outward": true,
          "ca_fsa": true
        },
        "language": true,
        "keyword_targets": {
          "supported_match_types": ["broad", "phrase", "exact"]
        },
        "negative_keywords": {
          "supported_match_types": ["broad", "exact"]
        }
      }
    },
    "content_standards": {
      "supports_local_evaluation": true,
      "supported_channels": ["display", "olv"],
      "supports_webhook_delivery": false
    },
    "audience_targeting": {
      "supported_identifier_types": ["hashed_email", "hashed_phone"],
      "supports_platform_customer_id": false,
      "supported_uid_types": ["uid2", "rampid"],
      "minimum_audience_size": 500,
      "matching_latency_hours": { "min": 1, "max": 24 }
    },
    "conversion_tracking": {
      "multi_source_event_dedup": false,
      "supported_event_types": ["purchase", "lead", "add_to_cart", "view_content"],
      "supported_action_sources": ["website", "app"],
      "attribution_windows": [
        { "post_click": [{ "interval": 7, "unit": "days" }, { "interval": 28, "unit": "days" }], "post_view": [{ "interval": 1, "unit": "days" }, { "interval": 7, "unit": "days" }] }
      ]
    },
    "portfolio": {
      "publisher_domains": ["example.com", "news.example.com"],
      "primary_channels": ["display", "olv"],
      "primary_countries": ["US", "CA"]
    }
  },
  "extensions_supported": ["acmecorp"],
  "last_updated": "2025-01-23T10:00:00Z"
}

This tells buyers:

AdCP versions: Version 1
Protocols: Media buy only
Auth model: Agent-trusted (require_operator_auth: false) — authenticate once, declare brands via sync_accounts
Billing: Operator or agent billing; default is operator
Country targeting: Available (ISO 3166-1 alpha-2: US, GB, etc.)
Region targeting: Available (ISO 3166-2: US-NY, GB-SCT, etc.)
Metro targeting: Nielsen DMA only (US market)
Postal targeting: US ZIP, UK outward codes, Canadian FSA
Audience targeting: Accepts hashed email, hashed phone, UID2, and RampID; minimum matched audience size of 500; matching latency 1–24 hours
Conversion tracking: Accepts purchase, lead, add_to_cart, view_content events from website/app; no multi-source dedup
Extensions: Vendor-specific data in ext.acmecorp

Multi-protocol agent

An agent can implement multiple protocols from a single endpoint. This is common for sellers that manage both media buying and creative generation — the buyer calls all tasks on the same URL.

{
  "$schema": "/schemas/protocol/get-adcp-capabilities-response.json",
  "status": "completed",
  "adcp": {
    "major_versions": [3],
    "idempotency": { "supported": true, "replay_ttl_seconds": 86400 }
  },
  "supported_protocols": ["media_buy", "creative"],
  "account": {
    "require_operator_auth": false,
    "supported_billing": ["operator"]
  },
  "media_buy": {
    "features": {
      "inline_creative_management": true
    },
    "portfolio": {
      "publisher_domains": ["news.example.com"],
      "primary_channels": ["display", "olv"]
    }
  },
  "creative": {
    "has_creative_library": true,
    "supports_generation": true,
    "supports_transformation": false,
    "supports_compliance": false,
    "bills_through_adcp": true
  }
}

This agent supports:

Media Buy Protocol: Product discovery, media buying, delivery reporting
Creative Protocol: Creative library management, AI-powered creative generation, variant-level delivery analytics via get_creative_delivery
Shared account: A single account established via sync_accounts applies to both protocols

When supported_protocols includes "creative", the buyer can call Creative Protocol tasks (list_creative_formats, sync_creatives, get_creative_delivery, etc.) on this agent. See Creative capabilities on sales agents.

Geo Standards Reference

Level	System	Examples
Country	ISO 3166-1 alpha-2	`US`, `GB`, `DE`, `CA`
Region	ISO 3166-2	`US-NY`, `GB-SCT`, `DE-BY`, `CA-ON`
Metro (US)	`nielsen_dma`	`501` (NYC), `803` (LA), `602` (Chicago)
Metro (UK)	`uk_itl2`	`UKI` (London), `UKD` (North West)
Metro (EU)	`eurostat_nuts2`	`DE30` (Berlin), `FR10` (Île-de-France)
Postal (US)	`us_zip`	`10001`, `90210`
Postal (US)	`us_zip_plus_four`	`10001-1234`
Postal (UK)	`gb_outward`	`SW1`, `EC1`, `M1`
Postal (UK)	`gb_full`	`SW1A 1AA`
Postal (CA)	`ca_fsa`	`K1A`, `M5V`

Migration from list_authorized_properties (v2)

The list_authorized_properties task was removed in v3. If migrating from v2:

Old Field	New Location
`publisher_domains`	`media_buy.portfolio.publisher_domains`
`primary_channels`	`media_buy.portfolio.primary_channels`
`primary_countries`	`media_buy.portfolio.primary_countries`
`portfolio_description`	`media_buy.portfolio.description`
`advertising_policies`	`media_buy.portfolio.advertising_policies`
`last_updated`	`last_updated` (top level)

New fields:

adcp.major_versions - Version compatibility
supported_protocols - Which domain protocols are supported
media_buy.features - Optional feature support
media_buy.execution.axe_integrations - Ad exchange support
media_buy.execution.creative_specs - VAST/MRAID versions
media_buy.execution.targeting - Geo targeting granularity

Error Handling

Error Code	Description	Resolution
`AUTH_MISSING`	No credentials presented	Provide credentials via auth header
`AUTH_INVALID`	Credentials rejected (expired / revoked)	Human credential rotation required
`VERSION_UNSUPPORTED`	Declared `adcp_major_version` not in seller’s `major_versions`	Call without `adcp_major_version` to discover supported versions, then retry
`INTERNAL_ERROR`	Server error	Retry with backoff

Best Practices

1. Cache Capabilities Capabilities rarely change. Cache results and use last_updated for staleness detection. 2. Check Protocol Support First Before accessing protocol-specific fields, verify the protocol is in supported_protocols. 3. Check Before Requesting Don’t send postal areas for a system the seller doesn’t support. Don’t request features the seller doesn’t support. 4. Fail Fast on Incompatibility If a seller doesn’t support required capabilities, skip them early rather than discovering failures later. 5. Read the Auth Model Before Proceeding Check account.require_operator_auth immediately after discovery. Agent-trusted and operator-scoped flows diverge significantly: the former uses a single credential for all brands and operators, the latter requires per-operator credentials and sessions. 6. Use Protocol Version for Routing Route requests to appropriate API versions based on adcp.major_versions.

Next Steps

After discovering capabilities:

Set up accounts: Follow the auth model from account.require_operator_auth — see Accounts and Agents
Filter products: Use get_products with capability-aware filters
Validate properties: Fetch publisher adagents.json files for property definitions
Create buys: Use create_media_buy with supported features

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Accounts and Agents - Auth models, account setup, billing
adagents.json Specification - Publisher authorization files
Product Filters - Capability-aware filtering
Content Standards - Brand safety configuration

Documentation Index

​Tool-Based Discovery

​Version Negotiation

​Request Parameters

​Response Structure

​adcp

​idempotency

​supported_protocols

​specialisms

​account

​Auth models

​media_buy

​reporting_delivery_methods

​features

​content_standards

​execution

axe_integrations

creative_specs

targeting

​audience_targeting

​conversion_tracking

​portfolio

​signals

​creative

​governance

​property_features

​creative_features

​content_standards

​policy_registry

​measurement

​metrics

​compliance_testing

​webhook_signing

​extensions_supported

​experimental_features

​wholesale_feed_versioning

​wholesale_feed_webhooks

​The Capability Contract

​Common Scenarios

​Basic Capability Discovery

​Check multi-protocol support

​Filter sellers by capability

​Use Capabilities to Build Targeting

​Local Inventory Example (Radio, DOOH)

​Response Example

​Multi-protocol agent

​Geo Standards Reference

​Migration from list_authorized_properties (v2)

​Error Handling

​Best Practices

​Next Steps

​Learn More

Tool-Based Discovery

Version Negotiation

Request Parameters

Response Structure

adcp

idempotency

supported_protocols

specialisms

account

Auth models

media_buy

reporting_delivery_methods

features

content_standards

execution

audience_targeting

conversion_tracking

portfolio

signals

creative

governance

property_features

creative_features

content_standards

policy_registry

measurement

metrics

compliance_testing

webhook_signing

extensions_supported

experimental_features

wholesale_feed_versioning

wholesale_feed_webhooks

The Capability Contract

Common Scenarios

Basic Capability Discovery

Check multi-protocol support

Filter sellers by capability

Use Capabilities to Build Targeting

Local Inventory Example (Radio, DOOH)

Response Example

Multi-protocol agent

Geo Standards Reference

Migration from list_authorized_properties (v2)

Error Handling

Best Practices

Next Steps

Learn More