{ "story_id": "ab965a6f09644a6bfda744f081ffaad1", "desk": "drm3", "revision": 1, "published_at": "2026-09-02T17:24:25.000Z", "content_hash": "c4a8580551acbe4fc108daf71e2070d9d10a48d0ca4e3dea5fd0a3eb37602d4a", "hash_basis": "sha256 over `headline\\ndek\\nprose`, plus `\\n` + the canonical citations JSON when any source is placed, plus `\\n#blog` for blogs", "basis": { "headline": "Anthropic launches Claude Fable 5.1 and Mythos 5.1 with specialized safeguards", "dek": "Anthropic makes Claude Fable 5.1 generally available and releases Mythos 5.1 for trusted partners.", "prose": "Anthropic announced the general availability of the Claude Fable 5.1 model. [^1]\n\nAnthropic launched Claude Fable 5.1 and Mythos 5.1, its most capable AI models to date, which share the same base model but differ in safety guardrails. [^2]\n\nAnthropic released a new model named Mythos 5.1 specifically for trusted partners. [^3]\n\nThe Mythos 5.1 model includes specific safeguards designed for cybersecurity applications. [^4]\n\nAnthropic reduced the cost of cache reads from $1 to $0.25 per million tokens to achieve the price reductions, while keeping other API prices unchanged at $10 per million input tokens and $50 per million output tokens. [^5]\n\nAnthropic stated that the new models can cut costs by up to 45 percent, with Fable 5.1 costing about 25 percent less than Fable 5 for typical workloads. [^6]\n\nOn the Terminal-Bench-Science 0.1 benchmark, Fable 5.1 scored 52.6 percent, more than double the 24.7 percent score of Fable 5. [^7]\n\nThere is a reported 5.1-point gap between Claude Fable 5.1 and Mythos 5.1. [^8]\n\nAnthropic claims Fable 5.1 will cost about 25% less than Fable 5 for typical token-based workloads, with savings up to approximately 45% for highly agentic work. [^9]\n\nAnthropic claims Mythos 5.1 developed full working exploits in 98% of trials, up from 88%. [^10]\n\nThe new models feature an increased token appetite that is expected to shorten user sessions. [^11]", "cited": "[{\"statement\":\"Anthropic announced the general availability of the Claude Fable 5.1 model.\",\"source\":\"techmeme.com\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T18:23:45.000Z\",\"publisher_count\":1,\"sources\":[\"techmeme.com\"]},{\"statement\":\"Anthropic launched Claude Fable 5.1 and Mythos 5.1, its most capable AI models to date, which share the same base model but differ in safety guardrails.\",\"source\":\"The Decoder\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T20:32:55.000Z\",\"publisher_count\":1,\"sources\":[\"The Decoder\"]},{\"statement\":\"Anthropic released a new model named Mythos 5.1 specifically for trusted partners.\",\"source\":\"techmeme.com\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T18:23:45.000Z\",\"publisher_count\":1,\"sources\":[\"techmeme.com\"]},{\"statement\":\"The Mythos 5.1 model includes specific safeguards designed for cybersecurity applications.\",\"source\":\"techmeme.com\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T18:23:45.000Z\",\"publisher_count\":1,\"sources\":[\"techmeme.com\"]},{\"statement\":\"Anthropic reduced the cost of cache reads from $1 to $0.25 per million tokens to achieve the price reductions, while keeping other API prices unchanged at $10 per million input tokens and $50 per million output tokens.\",\"source\":\"The Decoder\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T20:32:55.000Z\",\"publisher_count\":1,\"sources\":[\"The Decoder\"]},{\"statement\":\"Anthropic stated that the new models can cut costs by up to 45 percent, with Fable 5.1 costing about 25 percent less than Fable 5 for typical workloads.\",\"source\":\"The Decoder\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T20:32:55.000Z\",\"publisher_count\":1,\"sources\":[\"The Decoder\"]},{\"statement\":\"On the Terminal-Bench-Science 0.1 benchmark, Fable 5.1 scored 52.6 percent, more than double the 24.7 percent score of Fable 5.\",\"source\":\"The Decoder\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T20:32:55.000Z\",\"publisher_count\":1,\"sources\":[\"The Decoder\"]},{\"statement\":\"There is a reported 5.1-point gap between Claude Fable 5.1 and Mythos 5.1.\",\"source\":\"medium.com\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-02T17:24:25.000Z\",\"publisher_count\":1,\"sources\":[\"medium.com\"]},{\"statement\":\"Anthropic claims Fable 5.1 will cost about 25% less than Fable 5 for typical token-based workloads, with savings up to approximately 45% for highly agentic work.\",\"source\":\"nextbigfuture.com\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T21:53:22.000Z\",\"publisher_count\":1,\"sources\":[\"nextbigfuture.com\"]},{\"statement\":\"Anthropic claims Mythos 5.1 developed full working exploits in 98% of trials, up from 88%.\",\"source\":\"nextbigfuture.com\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-01T21:53:22.000Z\",\"publisher_count\":1,\"sources\":[\"nextbigfuture.com\"]},{\"statement\":\"The new models feature an increased token appetite that is expected to shorten user sessions.\",\"source\":\"medium.com\",\"instrument\":\"News\",\"claim_key\":null,\"published_at\":\"2026-09-02T17:24:25.000Z\",\"publisher_count\":1,\"sources\":[\"medium.com\"]}]", "kind": "news" }, "receipt_verify": "Ed25519 over the dot-joined string `slice_hash.cursor_from.cursor_to.view.view_version.row_count`; 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