---
title: "Changes to Create Message"
method: POST
path: "/messages"
---

# Changes to Create Message

`POST /messages`

> Every recorded change to this operation, newest first.

## Timeline

Changed in 1 of 2 revisions.

- **2026-11-03** `a4ddf2e02571`: 3 breaking, 2 warning, 14 info

## Changes

- **2026-11-03** `a4ddf2e02571`: 3 breaking, 2 warning, 14 info
  - removed `subschema #1, subschema #2` from the `tool_choice` request property `oneOf` list
  - the `thinking` request property type changed from `object` to no type
  - added `#/components/schemas/AnthropicThinkingContent, #/components/schemas/AnthropicRedactedThinkingContent` to the `content/items/` response property `oneOf` list for the response status `200`
  - removed the request property `thinking/budget_tokens`
  - removed the request property `thinking/type`
  - added the new optional request property `betas`
  - added the new optional request property `context_management`
  - added the new optional request property `metadata`
  - added the new optional request property `output_config`
  - added the new optional request property `tools/items/defer_loading`
  - added the new optional request property `tools/items/eager_input_streaming`
  - added the new optional request property `tools/items/strict`
  - added the new optional request property `tools/items/type`
  - the request property `tools/items/input_schema` became optional
  - added the new `system` enum value to the request property `messages/items/role`
  - request property `system` list-of-types was widened by adding types `array` to media type `application/json`
  - added `#/components/schemas/AnthropicThinkingContent, #/components/schemas/AnthropicRedactedThinkingContent` to the `messages/items/content/oneOf[subschema #2]/items/` request property `oneOf` list
  - added `subschema #1, subschema #2` to the `thinking` request property `oneOf` list
  - added `subschema #1, subschema #2` to the `tool_choice` request property `oneOf` list

---

[Operation](https://skmtc.dev/electronhub/apis/electron-hub-api/docs/messages/post.md) - [API](https://skmtc.dev/electronhub/apis/electron-hub-api.md) - [Page](https://skmtc.dev/electronhub/apis/electron-hub-api/changes/messages/post)