The Archive

Spawn builds multiplayer game world using agentic Fable-class models, enabling players to prompt AI agent Savi to modify environment in real-time.

Kimi 3.1 Pro 104BA-2.8T open-weights model claims parity with Fable-5.1; includes 2-3× faster inference API.

After months sitting on the sidelines of the frontier AI race, Google has finally launched its long-awaited Gemini 4 Argon model, claiming it can compete with the best the industry has to offer. Google says Argon delivers "frontier reasoning and improved performance across complex workflows," while cutting down on hedging, repetition, and the cliches that continue to plague AI chatbots. The company claims Argon outperforms rival models like GPT-6 Astra, Claude Fable 5.1, and Claude Opus 5.5 across a range of benchmarks, including coding, cybersecurity, science, finance, and law. Google says i...

Meta releases Muse Wonder, positioned as first Fable-class model, scoring GPT-6.1 equivalent on Artificial Analysis; llm-meta-ai plugin updated.

Simon Willison's September sponsors-only newsletter covers Fable models, LLM pricing competition, and mathematical capabilities.

Google announces Gemini 4 Argon with 1M context window, positioning against OpenAI Astra/Fable; limited access via Fairwind Program for government and cybersecurity professionals.

Anthropic called it "the strongest-performing model we've tested to date."

Incomplete article title lacks substantive detail on Claude Mythos and Fable 5.1 capabilities or release scope.

Simon Willison used Claude Fable 5.1 to build a WebAssembly-based video compressor tool via Claude Code.

A few weeks ago I felt like it would be fun to see if I can make one of those cheap Chinese CarPlay dongles run something other than the stock firmware. The idea was that rather than just forwarding CarPlay, why not do something more interesting with them? They all work quite similarly: they act as bridges between your car and the phone. From there they deal with video and audio streams and pass some other data through. Most of them also bring up a custom UI for pairing and have a web interface that your phone can reach for updates. Long story short: I had a conversation with Fable and Sol vi...

Simon Willison's August newsletter covers OpenAI security incidents, game-playing agents (Fable 5, Sol 5.6), and Claude auto mode with model releases roundup.

OpenAI launches GPT-6 Astra, a Claude Fable competitor priced at $10/$50 per million tokens, rolling out to ChatGPT Plus/Pro/Business/Enterprise and via API.

Fable 5.1 removes data retention policy and increases caching; Stratechery commentary on enterprise safeguards.

Anthropic releases Claude Fable/Mythos 5.1 with SOTA performance, 75% cache cost reduction, and 70% increased output token throughput.

Claude Fable 5.1 achieves 52.6% on Terminal-Bench-Science 0.1; Willison reports improved coding/creative task performance vs. prior versions.

Anthropic says its newest AI models, Fable 5.1 and Mythos 5.1, address criticisms from customers about price, data retention, and overzealous safeguards. The company claims Claude Fable 5.1 offers stronger performance than Fable 5, but costs around 25 percent less typically and up to 45 percent less for complex agentic tasks, thanks to reduced pricing on cached data that was already processed and stored. Along with the announcement, a slew of early impressions popped up, including from Every CEO Dan Shipper, who claims, "It's the strongest coding model we've used, but now it's fast, token-eff...

Fable 5.1 includes changes meant to reduce token cost and false-positive restrictions from the model's safeguards.

But then users start to report a weird bug. It's the 4th time your team has been trying to fix it. I mean... asking AI to fix it. Unfortunately, it seems like not even Fable can figure it out. You go talk to the person who worked on this feature. "So where does the data come from?" "Hmm... actually I don't know. Let me ask Claude." You sit next to each other watching an endless wall of text appear on the screen. Neither of you has any idea whether any of it is true but Claude seems very confident. [...] This project has become so convoluted, with so many layers and services, that no one on yo...

Claude Fable 5 and Claude Mythos 5 were first released on June 9, 2026. On June 12, 2026, Anthropic suspended access to both models to comply with U.S. Department of Commerce export controls; the Department lifted those controls on June 30, 2026, and Anthropic restored access on July 1, 2026 (Anthropic's statement: https://www.anthropic.com/news/fable-mythos-access ). These events are after Claude's training-data cutoff, so Claude knows about them only from this notice. If asked, Claude confirms them accurately and matter-of-factly — it doesn't deny the suspension happened — and otherwise tre...

Moonlight & Mayhem (Raccoon Heist by Codex + GPT-5.6 Sol Ultra) On Wednesday I wrote about One-shotting a Raccoon Heist game using Claude Fable 5 , where I had Claude Fable 5 build a full working game from a premise I generated with GPT-3 and DALL-E four years ago . I decided to pose the exact same prompt to Codex Desktop running GPT-5.6 Sol Ultra - the mode where Sol makes aggressive use of sub-agents - to see how it would do. It produced a much better game! Here's Moonlight & Mayhem - GitHub repository here , including the textures and prompts it generated using gpt-image-2 . Your browser d...

Back in 2022 I tweeted screenshots of a game concept generated by GPT-3 and some concept "art" created using DALL-E. Today, on the fourth anniversary of that tweet, I decided to see if Claude Fable 5 (running in Claude Code for web ) could build the entire game from the content of that tweet. It did a pretty good job of it! You can play the game here . Here's the GitHub repo , and a short video demo: Your browser does not support HTML5 video. How I built this This is the August 5th, 2022 tweet : My GPT-3 prompt back then was: Write a detailed product description of a computer game where a tea...

Release: llm-anthropic 0.26 Includes new features enabled by LLM 0.32 : New models: claude-fable-5 , claude-sonnet-5 , and claude-opus-5 . #75 , #76 Added server-side tools for WebSearch , WebFetch , CodeExecution , and AnthropicMCP , available through LLM's -T interface or Python tools= . The previous -o web_search* options have been removed in favor of -T WebSearch . #79 Upgraded to llm>=0.32 . Reasoning, tool calls, tool results, and server-side tool results now stream as typed events. Reasoning for llm CLI prompts now displays to standard error unless you pass --hide-reasoning/-R . Simpli...

APEX-Accounting benchmark from Mercor and Ramp tests frontier models on real accounting tasks; Claude-Fable-5 Max achieves 56.4% accuracy.

Anthropic releases Claude Opus 5 matching Fable performance at half the cost, demonstrating efficiency gains in model distillation.

Anthropic releases Claude Opus 5, matching Fable 5 frontier performance at half the cost, now leading Artificial Analysis leaderboard.

Opus 5 will be both cheaper and less restrictive than Fable, likely making it preferable in most use cases

Weeks after Anthropic's latest toe-to-toe with the US government, and days after an OpenAI security incident that dominated tech industry discussions, Anthropic on Thursday released its newest model, Claude Opus 5. The company said in a release that Opus 5 "comes close to the capabilities of Claude Fable 5 in many domains" and is much better at complex coding tasks. (Fable 5 is the public-facing Mythos-class model that drew the government's ire, was taken offline for a few weeks along with Mythos 5, and then brought back with even stronger cyber safeguards than before.) The Fable 5 concerns -...

"I don't think you get a model this strong and this quickly on the heels of Fable doing strictly distillation," one expert told TechCrunch.

Treasury Secretary Scott Bessent warned the U.S. government could sanction Chinese AI companies after White House officials accused Moonshot of distilling Anthropic's Fable model to develop Kimi K3.