Opus 5.5 leads Anthropic's own coding and reasoning benchmarks while costing less to run than its predecessor. Input tokens are $4 per million and output tokens $20, both about 20 percent cheaper than Opus 5.
In the News: September 22, 2026 (Midday)
Anthropic's Claude Opus 5.5 cuts agentic coding costs 40 percent and tops its own benchmarks; a researcher got Meta's Muse to export its full filesystem.
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Anthropic cuts agentic coding costs 40 percent with Claude Opus 5.5
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A researcher got Meta's Muse to hand over its own filesystem
James asked Muse, Meta's consumer AI assistant, to archive the files it could see and send them to his Google Drive. It did, delivering 6.8 GB that included the assistant's own instruction files, among them ones named SOUL.md,…