Anthropic-compatible

POST/v1/messages

Anthropic Messages requests are accepted and normalized by the Gateway. The top-level system field must be a string. The array form used by Anthropic's cache_control feature is not yet supported — sending an array returns 400 invalid_request_error. The anthropic-version header is accepted and forwarded unchanged.

Field	Type	Description
model	string · required	A model id from GET /v1/models.
max_tokens	integer · required	Max output tokens (Anthropic requires this). With extended thinking, the thinking budget counts against it — too low returns a `200` with empty content (see [Errors](/docs/errors)).
messages	array · required	Conversation turns, each { role, content }.
system	string	System prompt. Must be a string, not an array.
temperature	number	Sampling temperature, 0–1.
stream	boolean	Stream as Anthropic SSE events.

Request

curl https://api.atptoken.ai/v1/messages \
  -H "Authorization: Bearer atp-..." \
  -H "Content-Type: application/json" \
  -d '{
    "model": "<model from GET /v1/models>",
    "max_tokens": 256,
    "messages": [{"role": "user", "content": "hi"}]
  }'

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