- We've launched Claude Opus 5 (
claude-opus-5), a step-change improvement over Claude Opus 4.8. Claude Opus 5 supports a 1M token context window (both the default and the maximum), 128k max output tokens, and thinking on by default, at $5 / $25 USD per MTok, the same pricing as Claude Opus 4.8. It's available on the Claude API, Claude in Amazon Bedrock, Claude Platform on AWS, Claude on Google Cloud, and Claude in Microsoft Foundry. See What's new in Claude Opus 5 for new features, behavior changes, and migration guidance, and the models overview for complete specs.
- On Claude Opus 5, disabling thinking is allowed only at effort
high or below: thinking: {"type": "disabled"} with effort xhigh or max returns a 400 error, a breaking change from Claude Opus 4.8. See What's new in Claude Opus 5.
- Effort is the primary control for steering Claude Opus 5: the model supports the full ladder (
low, medium, high, xhigh, max), with max for capability-critical work.
- Mid-conversation tool changes are now in beta on Claude Fable 5, Claude Mythos 5, Claude Opus 4.8, and Claude Opus 5: add or remove tools between turns of a conversation while preserving the prompt cache. Include the
mid-conversation-tool-changes-2026-07-01 beta header in your requests.
- The
fallbacks parameter now supports a "default" mode, which applies Anthropic's recommended fallback models by refusal category. Server-side fallback is in beta, and the "default" mode requires the server-side-fallback-2026-07-01 beta header. See Refusals and fallback.
- We've removed fast mode for Claude Opus 4.7. Requests to
claude-opus-4-7 with speed: "fast" now return an error; unlike Claude Opus 4.6, they do not fall back to standard speed. Claude Opus 4.7 itself remains available at standard speed. To continue using fast mode, migrate to Claude Opus 5 or Claude Opus 4.8. Read more in Fast mode.