list_transformers

list_transformers discovers account-scoped creative transformers — the agent-offered, selectable units of build capability (voices, models, styles) used by build_creative.

Discover the transformers a creative agent offers for your account. A transformer is the creative analog of a media-buy product: an agent-offered, account-scoped, selectable unit of build capability (a voice, a model, a style, a director) with a typed configuration surface and per-account pricing. You discover transformers here, then select one with transformer_id in build_creative.

Response Time: ~1 second (account-scoped lookup)

Authentication: Account-scoped. Transformers, their enumerable option values, and pricing are resolved for the calling credential — including custom values you configured (e.g. cloned voices) that exist only for your account.

Request Schema: /schemas/3.0.19/creative/list-transformers-request.json Response Schema: /schemas/3.0.19/creative/list-transformers-response.json

Offered only by agents that set creative.supports_transformers: true in get_adcp_capabilities.

Why transformers

The set of render knobs a creative agent exposes — and their legal values — is account-specific and dynamic. Your configured voices aren’t a global enum or a list you hold; the agent knows them, and the set changes when you add one. So discovery flows agent → buyer, the same way get_products surfaces account-scoped inventory. list_transformers is that discovery surface for creative build capability.

The agent chooses granularity: a distinct voice or model may be its own transformer, or a single transformer may expose voice/model as an enumerable config param. Either way you use the same call — list transformers, expand a param if you want its values.

Request Parameters

Parameter	Type	Required	Description
transformer_ids	string[]	No	Return only these specific transformer IDs
input_format_ids	FormatID[]	No	Filter to transformers that accept any of these formats as input
output_format_ids	FormatID[]	No	Filter to transformers that can produce any of these output formats
name_search	string	No	Search transformers by name (case-insensitive partial match)
brief	string	No	Natural-language brief to rank/filter transformers and their option values (e.g. “warm female Spanish-language voiceover”). Curates to intent rather than returning the full set.
expand_params	string[]	No	Param field names for which to return the first page of account-scoped option values inline on params[].options[]. Omit for the lean default (descriptors only).
expand_pagination	object[]	No	Fetch the next page of a specific param’s options, scoped per { transformer_id, field, options_cursor } (cursor from a prior response’s params[].options_cursor). Use once you hold a cursor, instead of expand_params.
include_pricing	boolean	No	Include pricing_options on each transformer. Requires account.
account	AccountRef	Conditional	Required when include_pricing is true. Transformers are account-scoped regardless.
pagination	object	No	max_results and cursor (opaque cursor from previous response)

The expand mode

By default the response returns each transformer’s param schemas with small closed enums inlined (e.g. mastering_preset). To get the values of an account-scoped enumerable param (e.g. your voices), name it in expand_params — that returns the first page on params[].options[]. When a param’s values are truncated, its params[].options_cursor is set; fetch the next page by passing { transformer_id, field, options_cursor } in expand_pagination (each (transformer, param) pages independently). Values are brief-filtered — “warm Spanish female voice” narrows a 300-voice catalog to a handful instead of dumping all of them. There is no separate options endpoint; value enumeration (and its pagination) is a mode of this one tool.

Response

Field	Description
transformers	Array of transformer descriptors (see below)
errors	Optional array of task-specific errors and warnings
pagination	Pagination cursor when more transformers are available

Each transformer carries:

Field	Description
transformer_id	Stable id; pass to build_creative transformer_id
name	Human-readable name
input_format_ids / output_format_ids	What it accepts and produces. A build_creative target MUST be a subset of output_format_ids. Empty input_format_ids means it builds from a brief (pure generation).
params	Config knobs (see Transformer Param): field, type, value_source (inline/range/enumerable/free_text), allowed_values/minimum/maximum, options[]+options_cursor (when expanded), max_length (for free_text), default. free_text is an open buyer-authored string (e.g. a negative_prompt); a param MUST NOT be a generation-count knob — count rides max_variants/max_creatives.
pricing_options	Per-account rate card (when include_pricing). Uses the per_unit model (e.g. $/generated image,$/second). A pricing option may carry applies_to_output_format_ids to price different outputs differently (e.g. a multi-publisher template per publisher format); an unscoped option is the default, and an output matching no option (with no unscoped default) is rejected UNPRICEABLE_OUTPUT (no fallback). The applied option is echoed per-leaf on the build_creative response and reconciled via report_usage.

See Transformer schema for the complete object.

Common Scenarios

Discover voices for a brief, with values

test=false

import { testAgent } from '@adcp/sdk/testing';
import { ListTransformersResponseSchema } from '@adcp/sdk';

const result = await testAgent.listTransformers({
  account: { account_id: 'acct_acme' },
  brief: 'warm female Spanish-language voiceover',
  output_format_ids: [{ agent_url: 'https://creative.audiostack.example', id: 'audio_vo' }],
  expand_params: ['voice'],
  include_pricing: true,
});

const parsed = ListTransformersResponseSchema.parse(result);
for (const t of parsed.transformers) {
  console.log(t.transformer_id, t.name);
  const voice = t.params?.find((p) => p.field === 'voice');
  for (const opt of voice?.options ?? []) console.log('  voice:', opt.value, opt.metadata);
}

import asyncio
from adcp.testing import test_agent
from adcp import ListTransformersResponse

async def main():
    result = await test_agent.list_transformers(
        account={"account_id": "acct_acme"},
        brief="warm female Spanish-language voiceover",
        output_format_ids=[{"agent_url": "https://creative.audiostack.example", "id": "audio_vo"}],
        expand_params=["voice"],
        include_pricing=True,
    )
    parsed = ListTransformersResponse.model_validate(result)
    for t in parsed.transformers:
        print(t.transformer_id, t.name)

asyncio.run(main())

Then build with the selected transformer

Pass the chosen transformer_id and a typed config (keyed by each param’s field) to build_creative:

test=false

{
  "transformer_id": "audiostack_voiceover",
  "config": { "voice": "isaac", "speaking_rate": 1.1, "mastering_preset": "podcast" },
  "creative_manifest": { "format_id": { "agent_url": "https://creative.audiostack.example", "id": "script" }, "assets": { "script": { "asset_type": "text", "content": "Discover the new winter collection." } } },
  "target_format_id": { "agent_url": "https://creative.audiostack.example", "id": "audio_vo" },
  "account": { "account_id": "acct_acme" },
  "idempotency_key": "0c1d2e3f-4a5b-6c7d-8e9f-a0b1c2d3e4f5"
}

Error Handling

Code	Meaning	Recovery
AUTH_MISSING	include_pricing requested without a resolvable account	Supply account / authenticate
INVALID_REQUEST	Malformed filter or pagination cursor	Correct the request

Unknown expand_params (a field no transformer exposes) are ignored, not an error — the param simply returns no options.

Learn More

• build_creative — select a transformer and produce creatives (incl. variants)
• get_adcp_capabilities — creative.supports_transformers discriminator
• Vendor pricing — the per_unit rate model