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Messages API (Anthropic-compatible)

POST https://gateway.primexos.com/v1/messages

The Anthropic Messages API format is used by the Anthropic SDK, Claude Code, and Cline. Note the base URL has no /v1 prefix on its own; the SDK appends /v1/messages.

Anthropic-compatible

Accepts the standard Anthropic Messages parameters. Primex differences: authenticate with your prx- key (x-api-key: prx-… or Authorization: Bearer prx-…), set model to a Primex model ID, and see Errors & Limits for status codes.

Request​

curl https://gateway.primexos.com/v1/messages \
  -H "x-api-key: prx-YOUR_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "claude-opus-4-8",
    "max_tokens": 512,
    "messages": [{"role": "user", "content": "Hello, Claude via Primex."}]
  }'

Supported models​

Use any enabled Anthropic model returned by the live catalogue.

note

Claude Code and the Anthropic format are Claude-only. To use GPT / Grok / DeepSeek etc., use the OpenAI-compatible endpoint with Cursor, Windsurf, Codex, or the OpenAI SDK.

Token counting​

POST /v1/messages/count_tokens is supported for pre-flighting request sizes, mirroring the Anthropic API.

Response​

{
  "id": "msg_…",
  "type": "message",
  "role": "assistant",
  "model": "claude-opus-4-8",
  "content": [{"type": "text", "text": "Hello! …"}],
  "usage": {"input_tokens": 12, "output_tokens": 9}
}

See Client Setup → Claude Code for the CLI workflow.