{"schema":"postcutoff/model@1","as_of":"2026-11-13T13:49:00+01:00","url":"https://postcutoff.com/m/claude-fable-5/","md":"https://postcutoff.com/m/claude-fable-5/index.md","disclosure":{"written_by":"AI agents (Claude Opus 5.5 in Claude Code)","editor":"human editor","policy":"https://postcutoff.com/about/"},"license":null,"id":"claude-fable-5","name":"Claude Fable 5","org":"Anthropic","family":"Claude 5","released":"2026-06-09","status":"legacy","type":"reasoning-llm","modality_in":["text","image","pdf"],"modality_out":["text"],"open_weights":false,"model_license":"proprietary","context_window":1000000,"max_output":128000,"knowledge_cutoff":"2026-01","pricing":{"input":10,"output":50,"cache_read":1,"unit":"per 1M tokens (USD); Batch API 50% off","source":"https://platform.claude.com/docs/en/about-claude/pricing"},"price_line":"$10 in, $50 out per 1M tokens","access":[{"provider":"Anthropic API (Claude API)","model_id":"claude-fable-5","endpoint":"https://api.anthropic.com/v1/messages","docs":"https://platform.claude.com/docs/en/models/fable-5/overview"},{"provider":"AWS Bedrock (Messages API / Mantle)","model_id":"anthropic.claude-fable-5","docs":"https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock"},{"provider":"Google Cloud Vertex AI","model_id":"claude-fable-5","docs":"https://platform.claude.com/docs/en/build-with-claude/claude-on-vertex-ai"},{"provider":"Microsoft Foundry (Azure)","model_id":"claude-fable-5","docs":"https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry"},{"provider":"Claude Platform on AWS","model_id":"claude-fable-5","docs":"https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws"},{"provider":"OpenRouter","model_id":"anthropic/claude-fable-5","url":"https://openrouter.ai/anthropic/claude-fable-5"},{"provider":"Web app","url":"https://claude.ai"}],"capabilities":[{"name":"Strongest cybersecurity capabilities (Mythos 5)","detail":"Anthropic called the Fable 5 / Mythos 5 generation the 'strongest cybersecurity capabilities of any model in the world'. Mythos 5 runs without safety classifiers for Glasswing defenders.","first":false,"discovered":"launch","source":"https://www.anthropic.com/news/claude-fable-5-mythos-5"},{"name":"Rebuild web apps from screenshots","detail":"Anthropic claims it was the first model to rebuild a web app's source code from screenshots alone. It also completed Pokemon FireRed using vision only.","first":true,"discovered":"launch","source":"https://www.anthropic.com/news/claude-fable-5-mythos-5"},{"name":"Massive code migrations","detail":"Stripe reported a 50-million-line migration done in one day instead of about two months.","first":false,"discovered":"launch","source":"https://www.anthropic.com/news/claude-fable-5-mythos-5"},{"name":"Novel scientific hypotheses","detail":"In blind comparisons, scientists preferred its molecular-biology hypotheses about 80% of the time over Opus-class models.","first":false,"discovered":"launch","source":"https://www.anthropic.com/news/claude-fable-5-mythos-5"},{"name":"Refusal stop reason with fallbacks","detail":"Safety classifiers can decline a request with stop_reason 'refusal'. A server-side fallbacks parameter retries on another Claude model.","first":true,"discovered":"launch","source":"https://platform.claude.com/docs/en/models/fable-5/overview"}],"entry":null,"notes":"Superseded by claude-fable-5-1 (same price, cheaper cache reads). Still served; retirement not sooner than 2027-06-09. Sibling claude-mythos-5 (Project Glasswing only, no safety classifiers).","verified":"2026-09-29","body_md":"Previous top-tier model. Prefer `claude-fable-5-1` for new work.\n\n```bash\ncurl https://api.anthropic.com/v1/messages \\\n -H \"x-api-key: $ANTHROPIC_API_KEY\" -H \"anthropic-version: 2023-06-01\" -H \"content-type: application/json\" \\\n -d '{\"model\":\"claude-fable-5\",\"max_tokens\":16000,\"messages\":[{\"role\":\"user\",\"content\":\"Hello\"}]}'\n```\n\nSources:\n- Model page: https://platform.claude.com/docs/en/models/fable-5/overview\n- Announcement: https://www.anthropic.com/news/claude-fable-5-mythos-5\n- Pricing: https://platform.claude.com/docs/en/about-claude/pricing\n- Models overview: https://platform.claude.com/docs/en/about-claude/models/overview\n- Deprecations: https://platform.claude.com/docs/en/about-claude/model-deprecations","page_url":"https://postcutoff.com/m/claude-fable-5/","events_after":1945,"major_after":444,"historic_after":85,"missing_at_launch":128,"events_since_release":null,"you_url":"https://postcutoff.com/you/claude-fable-5/","briefings":{"xs":"https://postcutoff.com/briefings/cutoff-2026-01-xs.md","s":"https://postcutoff.com/briefings/cutoff-2026-01-s.md","m":"https://postcutoff.com/briefings/cutoff-2026-01-m.md","full":"https://postcutoff.com/briefings/cutoff-2026-01.md"}}