Claude API in prototypes

Your HTML artifacts can call Claude via a built-in helper. No SDK or API key needed.

<script>
(async () => {
  const text = await window.claude.complete("Summarize this: ...");
  // or with a messages array:
  const text2 = await window.claude.complete({
    messages: [{ role: 'user', content: '...' }],
  });
})();
</script>

Calls default to claude-haiku-4-5 with a 1024-token output cap. The body may also set model (haiku/sonnet families only), max_tokens (up to 32000), system, tool_choice, and client tools — standard Messages API shapes, except each tool also carries run: async (input) => string and the helper executes tool calls in-page and loops (max 8 model calls), resolving with the final text. Handler throws become is_error tool_results. Server tools (web search etc.) are rejected; no streaming; rate-limited 15 calls/minute per user, loop iterations included. Shared artifacts run under the viewer's quota.