Anthropic just released Claude Fable 5.1, its newest frontier model for long-running coding, research, and agentic work.

So naturally, we’re putting it to the test LIVE. 🤖

Early testing suggests Fable 5.1 is faster, easier to work with, and capable of handling massive coding projects, long-form writing, and autonomous agent tasks more efficiently. Every even found that it used less than half as many tokens as Opus 5 in one internal test.

But it has some quirks too. It can blow past word counts, create unnecessary subagents, and occasionally keep working when you tell it to stop.

Today, Grant and Corey from The Neuron are testing those claims for themselves.

We’re putting Fable 5.1 through:

🧠 Complex research and knowledge work

💻 Coding and long-running agent workflows

✍️ Writing, editing, and instruction following

🤖 Autonomous tasks where Claude runs on its own

🛑 Constraint, budget, and STOP tests

🆚 Whatever else the live chat wants us to try

Anthropic also cut cached-input pricing by 75%, potentially making long-running Claude agents significantly cheaper to operate.

Can Fable 5.1 actually become the model you hand a giant task and walk away from?

Let’s find out live.

UPDATE: Our write-up on this livestream, with time-stamps: https://theneuron.ai/news/claude-fable-5-1-can-do-the-work-the-hard-part-is-managing-it/

🔗 Anthropic announcement:https://www.anthropic.com/claude-fable-and-mythos-5-1

🔗 Every’s Fable 5.1 Vibe Check:https://every.to/vibe-check/fable-5-1-vibe-check

📩 Subscribe to The Neuron for AI news, tools, and practical experiments without the hype:https://theneuron.ai/

BONUS: Claude Fable 5.1 LIVE: Testing Anthropic’s New AI Agent

The Neuron: AI Explained

BONUS: Claude Fable 5.1 LIVE: Testing Anthropic’s New AI Agent