Chat Smith has added Claude Sonnet 5 to its model lineup — Anthropic's most agentic Sonnet model to date, built for coding, complex multi-step tasks, and knowledge work, available now for all Chat Smith Pro users at no extra cost.
Anthropic launched Claude Sonnet 5 on June 30, 2026, replacing Sonnet 4.6 as the default model across Free and Pro plans on claude.ai. It sits between Haiku and Opus in Anthropic's lineup and, for the first time, delivers near-Opus-4.8 performance at mid-tier pricing — with a 1M-token context window and 128K max output tokens.
What makes Claude Sonnet 5 stand out
Strong agentic and coding benchmarks. Sonnet 5 scores 63.2% on SWE-bench Pro, up from Sonnet 4.6's 58.1%, and 85.2% on SWE-bench Verified. On Terminal-Bench 2.1 it reaches 80.4% — a 24.7-point jump over Sonnet 4.6 and the first time a mid-tier Sonnet model has beaten its Opus sibling on that benchmark.
Near-Opus performance on reasoning and knowledge work. Sonnet 5 scores 57.4% on Humanity's Last Exam with tools, just half a point below Opus 4.8's 57.9% — the closest any Sonnet model has come to Opus on that benchmark. On the GDPval-AA v2 knowledge work index it actually edges Opus 4.8, scoring 1,618 Elo against 1,615.
More reliable on long, autonomous tasks. Anthropic built Sonnet 5 to complete tasks where earlier Sonnet models tended to stop short. It conducts longer explorations, recovers better when tool calls fail, and sustains focus on complex multi-step workflows — with adaptive thinking on by default.
A 1M-token context window. Sonnet 5 ships with a 1 million-token context window as default — the same ceiling as Opus 4.8 — and a 128K max output, double the 64K limit of Sonnet 4.6. This makes it practical for large codebase reviews, long-document analysis, and extended agent runs without context management overhead.
Included in Chat Smith Pro — no extra cost
Claude Sonnet 5 is available immediately to all Chat Smith Pro subscribers. No upgrade, no additional charge — open the model picker and select Claude Sonnet 5 to get started.
Chat Smith's goal is to bring the best available AI models into one place, so users can choose the right tool for each task without switching platforms.
Claude Sonnet 5 is available now for all Chat Smith Pro users at https://chatsmith.io/model/claude-sonnet-5.
