Messages API

The Messages API is Anthropic's foundational prompt-response interface, released approximately two years prior to the talk in which it was discussed. It represents the baseline interaction model for Claude, structured around a simple request-reply cycle.

Lance Martin (Anthropic) characterizes it as essentially a "prompt response" paradigm — a straightforward, stateless call-and-response mechanism — contrasting it implicitly with more complex, long-horizon agentic interaction patterns that have developed since its release. →

The API's framing as a two-year-old foundation suggests it predates and underlies newer constructs built for extended, multi-step agent workflows, positioning it as the primitive layer upon which more sophisticated orchestration (such as that used in Claude Code) is built.