---
title: "Changes to Create a chat completion"
method: POST
path: "/ai/chat/completions"
---

# Changes to Create a chat completion

`POST /ai/chat/completions`

> Every recorded change to this endpoint, newest first.
> 99 revisions in range; 1 not diffed.

## Timeline

Changed in 3 of 99 revisions.

- **2026-09-26** `74024ca53801` — 2 info
- **2026-09-16** `a6a61a29ecdd` — 1 breaking, 4 warning, 4 info
- **2026-07-29** `f8c0ade27450` — 1 info

## Changes

- **2026-09-26** `74024ca53801` — 2 info
  - the request property `max_tokens` became nullable
  - the `max_tokens` request property default value `8192` was added
- **2026-09-16** `a6a61a29ecdd` — 1 breaking, 4 warning, 4 info
  - the `response_format` request property type changed from `object` to no type
  - removed the request property `guided_choice`
  - removed the request property `guided_json`
  - removed the request property `guided_regex`
  - removed the request property `response_format/type`
  - added the new optional request property `mode`
  - added the new optional request property `reasoning_effort`
  - added the new optional request property `region`
  - added `#/components/schemas/ResponseFormatText, #/components/schemas/ResponseFormatJsonObject, #/components/schemas/ResponseFormatJsonSchemaParam` to the `response_format` request property `oneOf` list
- **2026-07-29** `f8c0ade27450` — 1 info
  - added the new optional request property `service_tier`

---

[Operation](https://skmtc.dev/team-telnyx/apis/telnyx-api-2/docs/ai/chat/completions/post.md) · [API](https://skmtc.dev/team-telnyx/apis/telnyx-api-2.md) · [Page](https://skmtc.dev/team-telnyx/apis/telnyx-api-2/changes/ai/chat/completions/post)