---
title: "Create Message"
method: POST
path: "/ai/conversations/{conversation_id}/message"
tags: ["Conversations"]
---

# Create Message

`POST /ai/conversations/{conversation_id}/message`

Add a new message to the conversation. Used to insert a new messages to a conversation manually ( without using chat endpoint )

## Path parameters

- `conversation_id` string, uuid, required — The ID of the conversation

## Headers

- `Idempotency-Key` string

## Request body

- CreateMsgReq
  - `role` string, required
  - `content` string
  - `name` string
  - `tool_choice` union
    - string
    - object
  - `tool_calls` object[]
  - `tool_call_id` string
  - `sent_at` string, date-time
  - `metadata` object

## Response `200`

Successful Response

## Other responses

- `400` — Bad Request / Validation Failed (10015). Invalid, duplicate, empty, malformed, or overlong Idempotency-Key headers are rejected by Edge with HTTP 400 and error code 10015.
- `409` — A request with the same Idempotency-Key is still being processed (10036). Retry later with the same key and request.
- `413` — Payload Too Large. A request sent with an Idempotency-Key whose body exceeds the endpoint's Edge replay-protection limit (256 KB) is rejected before it reaches the service. Requests sent without the header are not subject to this limit.
- `422` — Validation Error. Reusing an Idempotency-Key with a different request body also returns 422 with error code 10027.
- `503` — Service unavailable (10016), including unavailable Edge idempotency protection for a keyed request.

## Changes

> 81 revisions in range; 1 not diffed.

- **2026-09-22** `9621f6123ebc` — 2 warning
  - added the new `10011` enum value to the `errors/items/code` response property for the response status `409`
  - added the new `domain_graduation_limit_exceeded` enum value to the `errors/items/code` response property for the response status `409`
- **2026-09-16** `a6a61a29ecdd` — 1 breaking, 1 warning, 6 info
  - the response's body type changed from `object` to no type for status `422`
  - removed the optional property `detail` from the response with the `422` status
  - added the new optional `header` request parameter `Idempotency-Key`
  - added `#/components/schemas/HTTPValidationError, #/components/schemas/inference-embedding_ErrorResponse` to the response body `anyOf` list for the response status `422`
  - …4 more

[Change history](https://skmtc.dev/team-telnyx/apis/telnyx-api-2/changes/ai/conversations/:conversation_id/message/post.md)

---

[API](https://skmtc.dev/team-telnyx/apis/telnyx-api-2.md) · [All operations](https://skmtc.dev/team-telnyx/apis/telnyx-api-2/llms.txt) · [OpenAPI document](https://skmtc.dev/team-telnyx/apis/telnyx-api-2/revisions/f6e9ed754d05?raw)