---
title: "Create a message (Anthropic-compatible)"
method: POST
path: "/v1/messages"
tags: ["Messages"]
---

# Create a message (Anthropic-compatible)

`POST /v1/messages`

## Request body

- object
  - `model` string, required — Model alias from config. Available: anthropic/*, gpt-5.5
  - `messages` object[], required
    - `role` 'user' | 'assistant', required
    - `content` string, required
  - `max_tokens` integer, required
  - `stream` boolean

## Response `200`

Message response from upstream provider

- object
  - `id` string
  - `type` string
  - `role` string
  - `content` object[]
    - `type` string
    - `text` string
  - `model` string
  - `stop_reason` string
  - `usage` object
    - `input_tokens` integer
    - `output_tokens` integer

## Other responses

- `401` — Invalid or missing master key
- `404` — Model not found in config

---

[API](https://skmtc.dev/berriai/apis/litellm-agent-platform-api.md) · [All operations](https://skmtc.dev/berriai/apis/litellm-agent-platform-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/berriai/litellm-agent-platform-api/revisions/63cf31f8069f/schema)