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Public story · 2026-08-10 · high
Opus 5's system prompt tells it to admit the suspension happened and point users to Anthropic's official explanation, per Simon Willison.
Why now: Willison published the system-prompt breakdown on August 9, about two months after the suspension it describes.
Anthropic scripted how Claude Opus 5 talks about its own suspension, per a system-prompt section Simon Willison surfaced on August 9.
Two shipped models, Fable 5 and Mythos 5, went dark for 19 days over export-control compliance. That's real downtime for anyone who'd already built on them, not a policy footnote.
Fable 5 and Mythos 5 launched June 9. Three days later, Anthropic pulled both to comply with Commerce Department export controls, per Willison's post. The controls lifted June 30, and access came back July 1. Rather than wait on a retrain to fold that history into the model, Anthropic wrote it straight into Opus 5's instructions.
The prompt tells the model to confirm the suspension "accurately and matter-of-factly" and not deny it happened. No spin, no denial. It also tells Opus 5 to defer to Anthropic's official statement instead of offering its own read on why the pause happened.
The phrasing is deliberate: confirm the fact, skip the spin, hand off to Anthropic's official statement instead of letting the model editorialize on why the pause happened.
Each link below shares sources, entities, or timing with this story.
Claude Opus built by Anthropic / Shared entities / Same source domain / Shared topic / Earlier coverage
Linked by a graph relationship (Claude Opus built by Anthropic); both cover Anthropic, July, Mythos; reported by the same outlet (simonwillison.net).
Claude Opus built by Anthropic / Shared entities / Shared topic / Earlier coverage
Linked by a graph relationship (Claude Opus built by Anthropic); both cover Anthropic, Claude Opus, Fable, July; overlapping topics (anthropic, business, claude).
Claude Opus built by Anthropic / Shared entities / Same source domain / Shared topic / Earlier coverage / Tension
Linked by a graph relationship (Claude Opus built by Anthropic); both cover Anthropic, July, Willison; reported by the same outlet (simonwillison.net).
Linked by a graph relationship (Claude Opus built by Anthropic); both cover Anthropic, Fable, Willison; reported by the same outlet (simonwillison.net).
Claude Opus built by Anthropic / Shared entities / Shared topic / Earlier coverage
Linked by a graph relationship (Claude Opus built by Anthropic); both cover Anthropic, Fable, July, Mythos; overlapping topics (anthropic, commerce).
Linked by a graph relationship (Claude Opus built by Anthropic); both cover Anthropic, Fable, July, Mythos; overlapping topics (anthropic, claude).
Linked by a graph relationship (Claude Opus built by Anthropic); both cover Anthropic, Commerce Department, Fable, Mythos; overlapping topics (access, anthropic).
Linked by a graph relationship (Claude Opus built by Anthropic); both cover Anthropic, Fable, July; overlapping topics (anthropic, claude, prompt, system).