We've launched Claude Opus 4 and Claude Sonnet 4, our latest models with extended thinking capabilities

Thursday, 22 May 2025

AI summary

Written by AI from the official notes. Check them for exact details.

Claude Opus 4 and Claude Sonnet 4 have been launched with enhanced thinking capabilities and new features.

Why it matters: Users of Claude models should explore new features for improved functionality and performance.

We've launched Claude Opus 4 and Claude Sonnet 4, our latest models with extended thinking capabilities. Learn more in Models overview.
The default behavior of extended thinking in Claude 4 models returns a summary of Claude's full thinking process, with the full thinking encrypted and returned in the signature field of thinking block output.
We've launched interleaved thinking in public beta, a feature that enables Claude to think in between tool calls. To enable interleaved thinking, use the beta header interleaved-thinking-2025-05-14.
We've launched the Files API in public beta, enabling you to upload files and reference them in the Messages API and code execution tool.
We've launched the Code execution tool in public beta, a tool that enables Claude to execute Python code in a secure, sandboxed environment.
We've launched the MCP connector in public beta, a feature that allows you to connect to remote MCP servers directly from the Messages API.
To increase answer quality and decrease tool errors, we've changed the default value for the top_p nucleus sampling parameter in the Messages API from 0.999 to 0.99 for all models. To revert this change, set top_p to 0.999. Additionally, when extended thinking is enabled, you can now set top_p to values between 0.95 and 1.
Our Go SDK has moved from beta to its first stable release.
We've included minute and hour level granularity to the Usage page of Console alongside 429 error rates on the Usage page.

Full release notes9 changes

We've launched Claude Opus 4 and Claude Sonnet 4, our latest models with extended thinking capabilities. Learn more in Models overview.
The default behavior of extended thinking in Claude 4 models returns a summary of Claude's full thinking process, with the full thinking encrypted and returned in the signature field of thinking block output.
We've launched interleaved thinking in public beta, a feature that enables Claude to think in between tool calls. To enable interleaved thinking, use the beta header interleaved-thinking-2025-05-14.
We've launched the Files API in public beta, enabling you to upload files and reference them in the Messages API and code execution tool.
We've launched the Code execution tool in public beta, a tool that enables Claude to execute Python code in a secure, sandboxed environment.
We've launched the MCP connector in public beta, a feature that allows you to connect to remote MCP servers directly from the Messages API.
To increase answer quality and decrease tool errors, we've changed the default value for the top_p nucleus sampling parameter in the Messages API from 0.999 to 0.99 for all models. To revert this change, set top_p to 0.999. Additionally, when extended thinking is enabled, you can now set top_p to values between 0.95 and 1.
Our Go SDK has moved from beta to its first stable release.
We've included minute and hour level granularity to the Usage page of Console alongside 429 error rates on the Usage page.