Release date: 2026-09-28. This update is based on the vendor’s announcement and was added to the Worksflow.ai guide on October 11, 2026.
Anthropic introduced Claude Sonnet 5.5 on September 28, 2026. It describes the model as a faster complement to Opus for well-scoped work, coding, and document creation, and reports changes to speed, task cost, and evaluation performance relative to Sonnet 5.
What the update means
Those comparisons are Anthropic’s published results, not a guarantee that every request will be faster or cheaper. Measure complete task cost, including retries and tool usage, and check model IDs and compatibility before replacing a production endpoint.
What to verify before you update a workflow
- Confirm the exact model or product identifier in the vendor’s live documentation.
- Check whether the announcement describes a general release, preview, or restricted rollout.
- Test the same representative tasks, tool calls, and failure cases used in your current workflow.
- Record the vendor’s source and the date your team checked it.
Official sources
Details and availability can change after publication. Recheck the source before acting on this guide.