Coverage of Anthropic's September 22, 2026 release, including availability, operating costs, evaluation methods and safeguards.
AWS confirmed on September 22 that Anthropic's Claude Opus 5.5 is available via Amazon Bedrock and a separate Claude Platform on AWS route, each with its own billing and feature set; these are distinct technical choices rather than guaranteed automatic migration for existing apps. Subsequent Anthropic documentation details operational caveats: batch processing offers half-price tokens but imposes a 24-hour completion window, 29-day result/storage retention from creation, and unordered outputs requiring custom_id matching. Separately, successful HTTP 200 responses can still contain refusals needing explicit checks, with a fallback beta rerouting only classifier refusals (not outages) and per-attempt usage tracking. Migration guidance also warns that unedited thinking blocks can still be invalidated if prior system prompts, tool definitions or messages change, with enforcement defaults varying by account creation date (August 31, 2026 cutoff) and an optional drop_block beta setting to bypass—not fix—such errors. None of this independently verifies Anthropic's performance claims for Opus 5.5.
Updated 2026.10.01 09:00 KST · 4/4 articles covered · Dates are article publication dates
Anthropic binds retained thinking to the instructions, tools and messages that preceded it. Integrations that rewrite earlier context can encounter a 400 error even when thinking blocks themselves are intact.
Anthropic's documentation separates classifier refusals from overload and rate limits, and identifies the serving model and per-attempt usage needed to audit a fallback.
Anthropic's discounted batch service requires teams to reconcile individual outcomes and retrieve results within 29 days of creation, even when processing finishes later.
Bedrock and Claude Platform on AWS expose different service experiences.
