Messages

Anthropic Messages Requests with AI Gateway

Create messages using the Anthropic Messages API format.

Endpoint

POST /v1/messages

Basic message

Create a non-streaming message.

Example request

generate.ts

import Anthropic from '@anthropic-ai/sdk';
 
const apiKey = process.env.AI_GATEWAY_API_KEY || process.env.VERCEL_OIDC_TOKEN;
 
const anthropic = new Anthropic({
  apiKey,
  baseURL: 'https://ai-gateway.vercel.sh',
});
 
const message = await anthropic.messages.create({
  model: 'anthropic/claude-opus-5',
  max_tokens: 150,
  messages: [
    {
      role: 'user',
      content: 'Write a one-sentence bedtime story about a unicorn.',
    },
  ],
  temperature: 0.7,
});
 
for (const block of message.content) {
  if (block.type === 'text') console.log('Response:', block.text);
}
console.log('Usage:', message.usage);

generate.py

import os
import anthropic
 
api_key = os.getenv('AI_GATEWAY_API_KEY') or os.getenv('VERCEL_OIDC_TOKEN')
 
client = anthropic.Anthropic(
    api_key=api_key,
    base_url='https://ai-gateway.vercel.sh'
)
 
message = client.messages.create(
    model='anthropic/claude-opus-5',
    max_tokens=150,
    messages=[
        {
            'role': 'user',
            'content': 'Write a one-sentence bedtime story about a unicorn.'
        }
    ],
    temperature=0.7,
)
 
for block in message.content:
    if block.type == "text":
        print('Response:', block.text)
print('Usage:', message.usage)

generate.sh

curl -X POST "https://ai-gateway.vercel.sh/v1/messages" \
  -H "Authorization: Bearer $AI_GATEWAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-opus-5",
    "max_tokens": 150,
    "messages": [
      {
        "role": "user",
        "content": "Write a one-sentence bedtime story about a unicorn."
      }
    ],
    "temperature": 0.7
  }'

Response format

{
  "id": "msg_123",
  "type": "message",
  "role": "assistant",
  "content": [
    {
      "type": "text",
      "text": "Once upon a time, a gentle unicorn with a shimmering silver mane danced through moonlit clouds, sprinkling stardust dreams upon sleeping children below."
    }
  ],
  "model": "anthropic/claude-opus-5",
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 15,
    "output_tokens": 28
  }
}

Streaming messages

Set stream: true to receive tokens as they are generated. See Streaming for the full example and the list of server-sent event types.

Last updated September 8, 2026

Anthropic Messages API

Streaming

Was this helpful?