---
title: "Changes to Create a message"
method: POST
path: "/anthropic/v1/messages"
---

# Changes to Create a message

`POST /anthropic/v1/messages`

> Every recorded change to this operation, newest first.

## Timeline

Changed in 1 of 2 revisions.

- **2026-11-03** `f87af696a63e`: 10 breaking, 2 warning, 7 info

## Changes

- **2026-11-03** `f87af696a63e`: 10 breaking, 2 warning, 7 info
  - the response property `id` became nullable for the status `200`
  - the response property `model` became nullable for the status `200`
  - the response property `role` became nullable for the status `200`
  - the response property `id` became optional for the status `200`
  - the response property `model` became optional for the status `200`
  - the response property `role` became optional for the status `200`
  - the response property `stop_reason` became optional for the status `200`
  - the response property `stop_sequence` became optional for the status `200`
  - the `role` response property const value `assistant` was removed for the status `200`
  - added `subschema #1, subschema #2, subschema #3, subschema #4, subschema #5, subschema #6, subschema #7, subschema #8, subschema #9, subschema #10, subschema #11, subschema #12, subschema #13, subschema #14, subschema #15, subschema #16, subschema #17` to the `content/items/` response property `oneOf` list for the response status `200`
  - added the new `assistant` enum value to the `role` response property for the response status `200`
  - added the new `undefined` enum value to the `role` response property for the response status `200`
  - added the media type `text/event-stream` for the response with the status `200`
  - added the optional property `container` to the response with the `200` status
  - added the optional property `context_management` to the response with the `200` status
  - added the optional property `usage/cache_creation_input_tokens` to the response with the `200` status
  - added the optional property `usage/cache_read_input_tokens` to the response with the `200` status
  - added the optional property `usage/iterations` to the response with the `200` status
  - added the optional property `usage/total_tokens` to the response with the `200` status

---

[Operation](https://skmtc.dev/neosantara/apis/neosantara-ai-api/docs/anthropic/v1/messages/post.md) - [API](https://skmtc.dev/neosantara/apis/neosantara-ai-api.md) - [Page](https://skmtc.dev/neosantara/apis/neosantara-ai-api/changes/anthropic/v1/messages/post)