Fast mode for Claude Opus 5.5 is now available on Claude in Microsoft Foundry for deployments hosted on Azure
By Steven Van ·
Opus 5.5 fast mode is available on Azure-hosted Claude deployments in Microsoft Foundry, which support Global Standard and US Data Zone Standard.
Fast mode for Claude Opus 5.5 is now available on Claude in Microsoft Foundry, for deployments hosted on Azure. The announcement comes from the Claude Platform release notes for October 15, 2026, and Anthropic gives no further detail about the Foundry rollout.
Which Foundry deployments are covered
Foundry offers two hosting options, chosen when the deployment is configured: Hosted on Azure and Hosted on Anthropic. Fast mode applies to the Hosted on Azure option. In that option, inference runs on an Anthropic-operated service on Azure infrastructure. It supports Global Standard and US Data Zone Standard deployment types, and prompts and completions stay within Azure.
Setting up a deployment
Deployments are created in the Foundry portal by selecting a Claude model such as claude-opus-5-5 from the model catalog. Each hosting option is listed as a separate model version in the deployment settings. Choosing Default settings configures Hosted on Azure automatically for models available in both options. Requests can authenticate with an Azure-issued API key or a Microsoft Entra ID token.
The same day's release notes also took fast mode for Opus 5.5 out of research preview on the Claude API, and they note it no longer needs the fast-mode-2026-02-01 beta header there.