Anthropic released Claude Fable 5.1 on Tuesday. The company says the model delivers stronger coding performance at a lower price than its predecessor. The launch arrives as a closely watched index of AI token prices falls to record lows.

Pricing Changes for Fable 5.1

Fable 5.1 costs roughly 25% less than Fable 5 for typical workloads. Savings can reach up to 45% for complex coding tasks. The reduction comes from a 75% cut to cache read costs, which now stand at $0.25 per million tokens. Standard input pricing stays at $10 per million tokens. Output pricing remains $50 per million tokens.

Coding Benchmarks and Early Feedback

On Terminal-Bench 4.0, an agentic coding evaluation, Fable 5.1 scored 55.8%. Fable 5 scored 42%. OpenAI’s GPT-5.6 Sol scored 52.3%.

Early-access partners shared specific results. The investment firm Millennium reported that Fable 5.1 identified the root cause of a rare software crash that had eluded the firm’s engineers for years. Cognition, the company behind the AI coding agent Devin, said it would migrate its traffic from Opus 5 to Fable 5.1 on launch day.

Falling Token Prices Across the Industry

The release coincides with a sharp drop in the LLM Token Expenditure Index tracked by Silicon Data. The index fell to 97 cents per million tokens on Monday. That marks its lowest reading since the index’s creation late last year and less than half its summer peak.

The decline has been driven in part by open-source Chinese models such as Moonshot’s Kimi K3. Price cuts from OpenAI on its GPT-5.6 models and the spread of dynamic pricing across frontier labs have also played a role, according to Syz Group investing chief Charles-Henry Monchau.

The slide could complicate the financial outlook for both Anthropic and OpenAI. Both companies confidentially filed for initial public offerings this summer. “Token deflation compresses the revenue line while compute commitments stay fixed,” Monchau wrote.

New Enterprise Data Controls

Alongside the model launch, Anthropic introduced Enterprise Frontier Safeguards. The system stores customer data in the customer’s own cloud infrastructure rather than on Anthropic’s servers.

The change addresses concerns that arose after the company imposed a 30-day data retention requirement on enterprise traffic for its Fable and Mythos models in June. Reuters reported in August that Anthropic had been coordinating with more than 100 customers, including Salesforce, to develop the new system.

Eligible customers can use Fable 5.1 with zero data retention immediately. The full safeguards system will roll out in phases beginning this fall.

Shares of major technology companies were lower on Tuesday. The Nasdaq Composite slid nearly 1%. The S&P 500 ticked down 0.4%.