---
title: "Changes to Send Message Async"
method: POST
path: "/v1/agents/{agent_id}/messages/async"
---

# Changes to Send Message Async

`POST /v1/agents/{agent_id}/messages/async`

> Every recorded change to this operation, newest first.

## Timeline

Changed in 3 of 36 revisions.

- **2025-10-03** `f0554a0bf8b2`: 3 info
- **2025-09-29** `ac8e1eb68404`: 4 warning, 4 info
- **2025-09-18** `3a2d48137c08`: 2 info

## Changes

- **2025-10-03** `f0554a0bf8b2`: 3 info
  - added the new optional request property `messages/items/anyOf[subschema #1: MessageCreate]/content/anyOf[subschema #1]/items/oneOf[subschema #1: TextContent]/signature`
  - added the new optional request property `messages/items/anyOf[subschema #1: MessageCreate]/content/anyOf[subschema #1]/items/oneOf[subschema #3: ToolCallContent]/signature`
  - added the new optional request property `messages/items/anyOf[subschema #1: MessageCreate]/content/anyOf[subschema #1]/items/oneOf[subschema #7: OmittedReasoningContent]/signature`
- **2025-09-29** `ac8e1eb68404`: 4 warning, 4 info
  - removed the optional property `created_by_id` from the response with the `200` status
  - removed the optional property `job_type` from the response with the `200` status
  - removed the optional property `last_updated_by_id` from the response with the `200` status
  - removed the optional property `updated_at` from the response with the `200` status
  - the response property `agent_id` became required for the status `200`
  - removed the `expired` enum value from the `status` response property for the response status `200`
  - removed the `pending` enum value from the `status` response property for the response status `200`
  - response property `agent_id` list-of-types was narrowed by removing types `null` from media type `application/json` of response `200`
- **2025-09-18** `3a2d48137c08`: 2 info
  - added the optional property `agent_id` to the response with the `200` status
  - added the optional property `background` to the response with the `200` status

---

[Operation](https://skmtc.dev/yu-code666/apis/letta-api/docs/v1/agents/:agent_id/messages/async/post.md) - [API](https://skmtc.dev/yu-code666/apis/letta-api.md) - [Page](https://skmtc.dev/yu-code666/apis/letta-api/changes/v1/agents/:agent_id/messages/async/post)