Compatibility & versions

Verified clients

JavaScript integration uses unmodified openai 7.45.1 and @anthropic-ai/sdk 1.3.0. The displayed Python examples use openai 3.41.0 and anthropic 2.3.0. All three displayed request forms run against local HTTP, PostgreSQL and the real worker with a deterministic provider fixture. Python streaming helpers have not been separately verified. Fixture evidence does not establish live provider availability.

Supported contracts

Chat Completions supports text, function tools and native chunks. Responses supports stateless text/function items and typed lifecycle events. Messages supports text/tool blocks and its own event sequence. Check the individual reference pages for their strict field schemas.

Version and latency limits

Messages requires anthropic-version: 2026-10-21. Its stream starts immediately and sends incremental text, supported provider-visible thinking and tool-argument fragments. Authoritative usage is finalized before successful message_stop. The public model list uses OpenAI shape; Anthropic Models pagination is not implemented.

Not supported

Stateful Responses retrieval, previous_response_id, background execution, hosted external-client tools and multimodal inputs are outside this subset. Chat and Responses expose validated optional generation controls only when the selected model advertises support. Accepting a field in the contract does not establish live support for every model. Unsupported input fails explicitly.