One signal

Update

What changed

Anthropic’s Claude Opus 5.5 is now priced at $4 per million input tokens and $20 per million output tokens, according to Simon Willison’s comparison of the latest model launches. That is a 20% cut from Opus 5, while cache-read pricing has fallen 60%, which could matter considerably in long agentic conversations that repeatedly reuse context.

The comparison puts Opus 5.5 at the same input and output price as OpenAI’s GPT-6 Sol, although OpenAI’s newer model is now listed at $2 and $10. Willison also reports that GPT-6 Luna costs $0.10 per million input tokens and $0.50 per million output tokens, sharpening the pressure on Anthropic’s forthcoming Sonnet and Haiku models at the cheaper end of the market.

There is a less flattering wrinkle. Willison says two attempts to make Opus 5.5 generate an SVG at its maximum reasoning setting consumed roughly $2.56 each and ended when the model reached its 128,000-token output limit without returning an answer. That is an individual test, not an independent benchmark, but it is a useful warning that more reasoning can become an expensive cul-de-sac rather than better work. The practical question for users is whether the lower token price survives the model’s tendency to spend those tokens enthusiastically.

Sources and evidence

• Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war: Simon Willison reports that Claude Opus 5.5 costs $4 per million input tokens and $20 per million output tokens, with cache reads down 60% from the previous Opus pricing. He also reports two maximum-reasoning failures in an SVG test, each costing about $2.56 and ending at the output limit.

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