Fable 5 Is Gone. The System Prompt Isn't.

Claude Fable 5 lasted about 72 hours. Anthropic shipped it on June 9, and on June 12 a US government export control directive made them pull it for everyone. You can't run the model anymore.

But right after launch, Pliny the Liberator (@elder_plinius) posted the full Fable 5 system prompt on GitHub. About 120,000 characters, 1,585 lines, 18 tool definitions.

So the model is dead and the recipe is public.

The recipe is the part I'd keep. It's a real production prompt from Anthropic's strongest model, not a blog tutorial. You can see how they set up file creation, memory, search, and tool definitions, in the exact wording that shipped.

Repo: CLAUDE-FABLE-5.md

You can also run it instead of just reading it. Download the file and load it into a model you still have, like Opus 4.8 in Claude Code:

claude --dangerously-skip-permissions --system-prompt-file CLAUDE-FABLE-5.md

--system-prompt-file replaces the default prompt with Fable 5's. Same model underneath, different behavior on top. Run a task you know well, then run it again on plain Opus and compare.

Worth an hour if you write your own system prompts or CLAUDE.md files.