Claude Fable

Evidence (16)

• 8Hacker News·8/12/2026model_release
  Grok 4.6 reaches AI index frontier at lower cost

  Grok 4.6 scores 61 on the Artificial Analysis Intelligence Index, tying the GPT-5.6 Sol max score and narrowing the gap to the top frontier models. It also shows strong agentic performance across knowledge work, banking, and terminal benchmarks while keeping pricing at $2/$6 per million input/output tokens.

• 4Simon Willison·8/9/2026framework_update
  Claude Opus 5 system prompt explains export-control handling

  This item quotes part of the Claude Opus 5 system prompt, which instructs the model to answer accurately about the temporary suspension and later restoration of access to Claude Fable 5 and Claude Mythos 5 due to U.S. export controls. It also says the model should avoid speculation, point users to Anthropic’s statement, and check for newer information when possible.

• 4Simon Willison·8/7/2026product_launch
  Codex Builds a Better Raccoon Heist Game with GPT-5.6 Sol Ultra

  Simon Willison compared the same one-shot game prompt across different coding agents and found Codex Desktop running GPT-5.6 Sol Ultra produced a more compelling Raccoon Heist game than a previous Claude Fable 5 attempt. The post also notes a visible bug in the generated game, which was later fixed with a follow-up prompt, and includes the full Codex transcript plus repository assets generated during the session.

• 7Anthropic News·8/7/2026framework_update
  Anthropic updates Fable 5 biology safeguards

  Anthropic says it has improved Claude Fable 5’s biology safeguards to reduce false positives and unnecessary fallbacks to a less capable model. The company says the change cuts biology-related fallbacks by about 85%, while maintaining stricter blocking for dual-use biology topics such as virology, toxicology, and molecular design.

• 4Simon Willison·8/5/2026product_launch
  Claude Fable 5 builds a raccoon heist game

  Simon Willison describes using Claude Fable 5 in Claude Code for web to generate a playable browser game based on an old raccoon-heist concept, with GitHub Pages used for rapid preview and iteration. The workflow combined the Claude agent with OpenAI's image generation API to fill in textures and visuals while the project was built and committed from mobile.

• 6The New Stack·7/29/2026model_release
  Claude Opus 5 vs. Fable 5: What the cheaper model trades off

  The article compares Anthropic’s Claude Opus 5 and Claude Fable 5, focusing on pricing, benchmark results, and hands-on reasoning tests. It concludes that Opus 5 is cheaper and often competitive, but Fable 5 remains the stronger general-access model overall in Anthropic’s own wording and in some evaluations.

• 6Hacker News·7/24/2026research
  Opus 5 Tops Artificial Analysis Intelligence Leaderboard

  Artificial Analysis reports Claude Opus 5 as the highest-scoring model on its Intelligence leaderboard, with Opus 5 variants ranked ahead of other leading systems such as Claude Fable 5 and GPT-5.6 Sol. The page compares models across intelligence, speed, latency, price, and context window using its multi-evaluation methodology.

• 5Hacker News·7/18/2026research
  Fable 5 Outperforms GPT-5.6 Sol on an NP-Hard Optimization Benchmark

  A benchmark comparison on an unpublished fiber-network optimization problem found Claude Fable 5 to be the strongest model overall, with more consistent results than GPT-5.6 Sol. The report also suggests the native /goal mode is not a universal performance boost: it sometimes improves results, but often changes the search path in ways that can also hurt outcomes.

• 7The New Stack·7/18/2026model_release
  Claude Fable 5 added permanently to subscription plans

  Anthropic says Claude Fable 5 will be included in all Max and Team Premium plans starting July 20, at 50% of usage limits. Pro and Team Standard users will still access it through usage credits and will receive a one-time $100 credit. The change reverses a planned move to remove the model from subscriptions, likely in response to competitive pressure and user demand.

• 5Hacker News·7/16/2026research
  Claude Fable 5 and GPT-5.6 Sol build AI music videos on a budget

  A Hacker News post describes an open-source harness that lets frontier models autonomously research, generate, watch, and edit a full music video within a fixed budget. The experiment compared Claude Fable 5 and GPT-5.6 Sol at $25 and $100, logging tool use, costs, and output quality across four runs that all completed successfully.

• 3Simon Willison·7/16/2026open_source
  Mermaid diagrams rendered as Unicode box art

  Simon Willison describes experimenting with a Rust-based terminal renderer for Mermaid diagrams found in the open-sourced Grok CLI codebase. He also prototyped running it in the browser through WebAssembly, producing a tool that displays Mermaid diagrams as Unicode box art. The post is a short developer-focused note about adapting an existing terminal component for web use.

• 8Hacker News·7/15/2026research
  Star Fleet Claims 20 Erdős Problem Solutions in Parallel

  Star Fleet, a Lean 4-based AI math system, claims it solved 20 Erdős problems using up to 20 parallel agent harnesses, each running a separate GPT-5.6 instance. The setup combines large-scale compute, theorem search, proof verification, and long-term dependency tracking to tackle open mathematics problems.

• 8The New Stack·7/11/2026model_release
  OpenAI, SpaceXAI and Meta spark an AI price war

  OpenAI, SpaceXAI, and Meta each launched or expanded new AI models within a 24-hour window, but the shared headline was pricing rather than capability. The article argues that frontier AI is increasingly competing on lower token costs and efficiency, signaling growing pressure on margins across leading model providers.

• 7Hacker News·7/9/2026research
  GLM 5.2 nearly matches a human bookkeeper on VAT returns

  A blog post reports that GLM 5.2, an open-weights AI model, completed a quarterly UK VAT return for a small business with near-perfect accuracy, missing the final VAT position by only 7 pence. The test used a sandboxed accounting workflow and measured the model’s ability to enter transactions into cloud accounting software via CLI tools.

• 6The New Stack·7/8/2026model_release
  Grok 4.5, GPT-5.5, and Claude Compared on Coding Builds

  A Hacker News post compared Grok 4.5, GPT-5.5, Claude Opus 4.8, and Claude Fable 5 on three one-shot coding tasks: a 3D Rubik's Cube, a particle gravity sandbox, and a Breakout game. The results showed different strengths across visual quality, physics behavior, and speed/cost, with Grok 4.5 standing out on latency and throughput while the Claudes excelled on the Rubik's Cube task.

• 2Hacker News·7/7/2026product_launch
  Claude Fable 5 access extended on paid plans through July 12

  Claude says access to Fable 5 will remain available on all paid plans through July 12, extending the current access window. The post does not provide additional product details beyond the temporary availability change.