---
title: "Preview First Messages"
method: POST
path: "/campaigns/audience-builds/{build_id}/preview-messages"
tags: ["campaigns"]
---

# Preview First Messages

`POST /campaigns/audience-builds/{build_id}/preview-messages`

Representative first blasts for a build's top members; stores nothing.

## Path parameters

- `build_id` string, required

## Request body

- PreviewFirstMessagesRequest
  - `goal` string, nullable
  - `agent_instructions` string, nullable
  - `count` integer
  - `booking` CampaignBookingSelection — The operator's final answer to "what does a yes book?" for one campaign.
    - `office_handles_booking` boolean
    - `job_type_id` integer, nullable
    - `business_unit_id` integer, nullable
    - `team_ids` integer[]
    - `visit_label` string

## Response `200`

Successful Response

- PreviewFirstMessagesResponse
  - `messages` PreviewFirstMessage[], required
    - `st_customer_id` string, nullable
    - `member_key` string
    - `customer_name` string, required
    - `phone` string
    - `body` string, required
    - `evidence_title` string
    - `fallback_reason` string, nullable
  - `sender_name` string
  - `company_name` string

## Other responses

- `404` — Not found
- `422` — Validation Error

## Changes

- **2026-09-16** `c14a8fc770d0` — 1 info
  - added the new optional request property `booking`
- **2026-09-10** `8eb1d6b3ce25` — 2 breaking, 1 info
  - the response property `messages/items/st_customer_id` became optional for the status `200`
  - response property `messages/items/st_customer_id` list-of-types was widened by adding types `null` to media type `application/json` of response `200`
  - added the optional property `messages/items/member_key` to the response with the `200` status
- **2026-09-02** `d96feef8e2ef` — 1 info
  - endpoint added

[Change history](https://skmtc.dev/noso/apis/crucible-backend-api/changes/campaigns/audience-builds/:build_id/preview-messages/post.md)

---

[API](https://skmtc.dev/noso/apis/crucible-backend-api.md) · [All operations](https://skmtc.dev/noso/apis/crucible-backend-api/llms.txt) · [OpenAPI document](https://skmtc.dev/noso/apis/crucible-backend-api/revisions/c14a8fc770d0?raw)