Claude Sonnet 5.5 Debuts as Anthropic's Default Model, 30% Faster and Cheaper

Anthropic's claude-code v2.1.284 release adds Claude Sonnet 5.5 (claude-sonnet-5-5) as the new default Sonnet model on the API, with 1M context and pricing at $2/$10 per Mtok plus $0.20/Mtok cache reads. Anthropic says it runs 30%+ faster and costs up to 30% less than Sonnet 5 for most work while beating it on every benchmark, at the same list price. The same release also surfaces real dollar spend tracking in /usage and the status line, and Sonnet 5.5 now powers the free tier on claude.ai.

• v2.1.284 sets claude-sonnet-5-5 as the default Sonnet model with 1M context, $2/$10 per Mtok, and $0.20/Mtok cache reads
• The release adds dollar amounts to gateway spend limits in /usage and the status line, e.g. "$271.40 / $500.00 spent this month", plus used_usd/limit_usd fields in rate_limits.spend_limit
• Sonnet 5.5 now runs claude.ai's free tier, which Willison notes is more capable than ChatGPT's free-tier Luna 5.6 model
• Caveat: the claims that Sonnet 5.5 beats Sonnet 5 on every benchmark and runs 30%+ faster/cheaper come from Anthropic's own announcement, not independent benchmarking
• Haiku 5.5 is promised "in the coming weeks" but is not part of this release

Bottom line If you build on Anthropic's API, update to claude-code v2.1.284, switch to Sonnet 5.5 for the cost/speed gains, and check the new /usage spend-limit display before your next invoice.