{"slug":"claude-fable-5","id":"claude-fable-5","type":"model","title":"Claude Fable 5","description":"Anthropic's most capable widely released model. First public Mythos-class model, released under Project Glasswing safeguards. 80.3% SWE-bench Pro. 1M context, adaptive thinking always on.","last_updated":"2026-06-10","last_verified":"2026-06-10","verification_status":"verified","markdown_url":"/content/models/claude-fable-5.md","html_url":"/models/claude-fable-5","api_url":"/api/v1/models/claude-fable-5.json","content_hash":"50bf0fc6d4e12fb88b4e4ea0b57092e673cfe4327b47f823292c57dde28adf2b","sha256":"50bf0fc6d4e12fb88b4e4ea0b57092e673cfe4327b47f823292c57dde28adf2b","provider":"Anthropic","model_type":"proprietary","api_model_id":"claude-fable-5","capabilities":["function_calling","vision","web_search","code_execution","structured_output","streaming","prompt_caching","tool_search","long_context","reasoning","adaptive_thinking"],"availability_status":"available","deprecated":false,"tool_schema_format":"anthropic","pricing_confidence":"high","model_listing_confidence":"high","benchmark_confidence":"low","sources":[{"title":"Anthropic: Claude Fable 5 and Claude Mythos 5","url":"https://www.anthropic.com/news/claude-fable-5-mythos-5"},{"title":"Anthropic Claude models overview","url":"https://platform.claude.com/docs/en/about-claude/models/overview"},{"title":"TechCrunch: Anthropic releases Claude Fable 5","url":"https://techcrunch.com/2026/06/09/anthropic-released-claude-fable-5-its-most-powerful-model-publicly-days-after-warning-ai-is-getting-too-dangerous/"}],"benchmark_sources":[{"title":"Anthropic: Claude Fable 5 and Claude Mythos 5","url":"https://www.anthropic.com/news/claude-fable-5-mythos-5"},{"title":"AI Future Ready benchmark methodology","url":"https://ai-future-ready.com/guides/benchmark-methodology"}],"pricing":{"input":"$10.00 / 1M tokens","output":"$50.00 / 1M tokens","input_per_1m":10,"output_per_1m":50,"currency":"USD","note":"Double Opus 4.8 pricing. Uses the Opus 4.7 tokenizer: the same text produces roughly 30% more tokens than pre-4.7 Claude models."},"benchmarks":{"reasoning":99,"coding":99,"math":97,"writing":97,"multilingual":92,"speed":60},"context_window":"1M tokens","modality":["text","image"],"license":"Proprietary","tags":["anthropic","proprietary","text","image","frontier"],"website":"https://anthropic.com","release_date":"2026-06-09","relationships":{"links":[],"related":[{"id":"claude-haiku-4.5","title":"Claude Haiku 4.5","type":"model","html_url":"/models/claude-haiku-4.5","markdown_url":"/content/models/claude-haiku-4.5.md","shared_tags":["anthropic","proprietary","text","image"],"score":8},{"id":"claude-opus-4.6","title":"Claude Opus 4.6","type":"model","html_url":"/models/claude-opus-4.6","markdown_url":"/content/models/claude-opus-4.6.md","shared_tags":["anthropic","proprietary","text","image"],"score":8},{"id":"claude-opus-4.7","title":"Claude Opus 4.7","type":"model","html_url":"/models/claude-opus-4.7","markdown_url":"/content/models/claude-opus-4.7.md","shared_tags":["anthropic","proprietary","text","image"],"score":8},{"id":"claude-opus-4.8","title":"Claude Opus 4.8","type":"model","html_url":"/models/claude-opus-4.8","markdown_url":"/content/models/claude-opus-4.8.md","shared_tags":["anthropic","proprietary","text","image"],"score":8},{"id":"claude-sonnet-4.6","title":"Claude Sonnet 4.6","type":"model","html_url":"/models/claude-sonnet-4.6","markdown_url":"/content/models/claude-sonnet-4.6.md","shared_tags":["anthropic","proprietary","text","image"],"score":8},{"id":"gemini-3-flash","title":"Gemini 3 Flash","type":"model","html_url":"/models/gemini-3-flash","markdown_url":"/content/models/gemini-3-flash.md","shared_tags":["proprietary","text","image"],"score":5}],"explicit":{}},"metadata":{"title":"Claude Fable 5","type":"model","id":"claude-fable-5","provider":"Anthropic","model_type":"proprietary","api_model_id":"claude-fable-5","release_date":"2026-06-09","description":"Anthropic's most capable widely released model. First public Mythos-class model, released under Project Glasswing safeguards. 80.3% SWE-bench Pro. 1M context, adaptive thinking always on.","last_updated":"2026-06-10","last_verified":"2026-06-10","availability_status":"available","deprecated":false,"tool_schema_format":"anthropic","pricing_confidence":"high","model_listing_confidence":"high","benchmark_confidence":"low","context_window":"1M tokens","website":"https://anthropic.com","license":"Proprietary","modality":["text","image"],"tags":["anthropic","proprietary","text","image","frontier"],"pricing":{"input":"$10.00 / 1M tokens","output":"$50.00 / 1M tokens","input_per_1m":10,"output_per_1m":50,"currency":"USD","note":"Double Opus 4.8 pricing. Uses the Opus 4.7 tokenizer: the same text produces roughly 30% more tokens than pre-4.7 Claude models."},"benchmarks":{"reasoning":99,"coding":99,"math":97,"writing":97,"multilingual":92,"speed":60},"capabilities":["function_calling","vision","web_search","code_execution","structured_output","streaming","prompt_caching","tool_search","long_context","reasoning","adaptive_thinking"],"sources":[{"title":"Anthropic: Claude Fable 5 and Claude Mythos 5","url":"https://www.anthropic.com/news/claude-fable-5-mythos-5"},{"title":"Anthropic Claude models overview","url":"https://platform.claude.com/docs/en/about-claude/models/overview"},{"title":"TechCrunch: Anthropic releases Claude Fable 5","url":"https://techcrunch.com/2026/06/09/anthropic-released-claude-fable-5-its-most-powerful-model-publicly-days-after-warning-ai-is-getting-too-dangerous/"}],"benchmark_sources":[{"title":"Anthropic: Claude Fable 5 and Claude Mythos 5","url":"https://www.anthropic.com/news/claude-fable-5-mythos-5"},{"title":"AI Future Ready benchmark methodology","url":"https://ai-future-ready.com/guides/benchmark-methodology"}],"best_for":["Hardest reasoning and research tasks","Long-horizon agentic coding","High-stakes knowledge work","Scientific analysis"]},"content_text":"# Claude Fable 5\n\nThe most capable model anyone can buy as of June 2026. Fable 5 is the first Mythos-class model Anthropic has released publicly -- the same underlying model as the restricted Claude Mythos 5, but with safeguards that block responses in specific high-risk areas like cybersecurity and biology. When a safeguard triggers (Anthropic says under 5% of sessions on average), the query is answered by Opus 4.8 instead.\n\nThe capability gap is real, not marketing. On SWE-bench Pro, Fable 5 scores 80.3% against 69.2% for Opus 4.8, 58.6% for GPT-5.5, and 54.2% for Gemini 3.1 Pro. Anthropic reports state-of-the-art results across software engineering, knowledge work, vision, and scientific research. Adaptive thinking is always on -- there is no extended-thinking toggle -- and the model decides how much reasoning each task needs.\n\nThe costs are equally real. At $10/$50 per million tokens it is double Opus 4.8, and it uses the Opus 4.7 tokenizer, so the same text produces roughly 30% more tokens than on pre-4.7 models. One policy caveat matters for enterprises: Anthropic requires 30-day data retention on all Fable 5 traffic, even for customers with prior zero-retention agreements.\n\n**When to pick something else:** If your workload doesn't need the absolute frontier, Opus 4.8 delivers most of the capability at half the price with no retention caveat. For high-volume or latency-sensitive work, Sonnet 4.6 remains the practical default. If your domain regularly touches the safeguarded areas, the silent fallback to Opus 4.8 makes behavior harder to predict -- benchmark your actual traffic before committing.","content_length":3834,"generated_at":"2026-06-22"}