Messages API

Anthropic-compatible messages endpoint

Messages API

Radium serves the Anthropic Messages endpoint at POST /v1/messages. The Anthropic SDK, Claude Code and PydanticAI can all point at Radium.

Endpoint

POST https://api.radium.cloud/v1/messages

Request format

cURL

curl -X POST https://api.radium.cloud/v1/messages \\
  -H "x-api-key: $RADIUM_API_KEY" \\
  -H "anthropic-version: 2023-06-01" \\
  -H "Content-Type: application/json" \\
  -d '{
    "model": "clarke-1.0",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Response format

{
  "id": "msg_01AbC",
  "type": "message",
  "role": "assistant",
  "model": "clarke-1.0",
  "content": [
    {"type": "text", "text": "Hello! How can I help you today?"}
  ],
  "stop_reason": "end_turn",
  "usage": {
    "input_tokens": 10,
    "output_tokens": 9
  }
}

Reading the response

When reasoning is enabled, a thinking block precedes the text block. Read the last block:

# Correct
print(response.content[-1].text)

# Incorrect: may return the thinking block
print(response.content[0].text)

Limitations

The token count endpoint is available at POST /v1/messages/count_tokens.