{"schema":"postcutoff/event@1","as_of":"2026-11-13T13:49:00+01:00","url":"https://postcutoff.com/e/2026-06-30-claude-sonnet-5/","md":"https://postcutoff.com/e/2026-06-30-claude-sonnet-5/index.md","disclosure":{"written_by":"AI agents (Claude Opus 5.5 in Claude Code)","editor":"human editor","policy":"https://postcutoff.com/about/"},"license":null,"id":"2026-06-30-claude-sonnet-5","date":"2026-06-30","date_precision":"day","short_title":"Anthropic releases Claude Sonnet 5, \"the most agentic Sonnet yet\"","deck":null,"takeaway":"Claude Sonnet 5 (claude-sonnet-5) launched on June 30, 2026 at $2/$10 per million tokens.","category":"model-release","category_label":"Model releases","importance":3,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":[{"n":1,"title":"Introducing Claude Sonnet 5 (Anthropic)","url":"https://www.anthropic.com/news/claude-sonnet-5","type":"official","group":"primary","domain":"anthropic.com"},{"n":2,"title":"Claude Sonnet 5 System Card","url":"https://www.anthropic.com/claude-sonnet-5-system-card","type":"paper","group":"primary","domain":"anthropic.com"},{"n":3,"title":"Claude Sonnet 5 docs overview","url":"https://platform.claude.com/docs/en/models/sonnet-5/overview","type":"docs","group":"primary","domain":"platform.claude.com"},{"n":4,"title":"TechCrunch: Claude Sonnet 5 as a cheaper way to run agents","url":"https://techcrunch.com/2026/06/30/anthropic-launches-claude-sonnet-5-as-a-cheaper-way-to-run-agents/","type":"press","group":"press","domain":"techcrunch.com"},{"n":5,"title":"MacRumors: Sonnet 5 with near-Opus performance","url":"https://www.macrumors.com/2026/06/30/anthropic-claude-sonnet-5/","type":"press","group":"press","domain":"macrumors.com"}],"official":3,"filed":"2026-09-29","updated":"2026-09-29","orgs":["Anthropic"],"title":"Anthropic releases Claude Sonnet 5, \"the most agentic Sonnet yet\"","summary":"Claude Sonnet 5 (`claude-sonnet-5`) launched on June 30, 2026 at $2/$10 per million tokens. Anthropic said it performs close to Opus 4.8 at Sonnet cost. It became the default for Free and Pro users on July 1.","key_facts":["Released June 30, 2026; model id claude-sonnet-5; context 1M, 128K output","Price $2 input / $10 output per 1M tokens (introduced as through-Aug-31 pricing; Anthropic's page says it was made permanent Aug 10, 2026)","Humanity's Last Exam with tools: 51.2% vs Sonnet 4.6's 46.8% (Anthropic)","Default model for Free and Pro plans from July 1, 2026, replacing Sonnet 4.6","Cyber safeguards enabled by default"],"key_numbers":[],"tags":["llm","claude","sonnet","agents"],"science":null,"body_md":"## What happened\n\nSonnet 5 can make plans, use browsers and terminals, run autonomously, and check its own output without being asked. It is on the Claude API, Claude Platform on AWS, Bedrock and Microsoft Foundry, with Google Cloud following. Anthropic reported lower hallucination and sycophancy rates than Sonnet 4.6.\n\n## Why it matters\n\nIt moved Opus-4.8-class agentic ability to the default free tier just weeks after Mythos-class models reached the public.","disputed":[],"related":[{"id":"2026-09-28-claude-sonnet-5-5","url":"https://postcutoff.com/e/2026-09-28-claude-sonnet-5-5/","date":"2026-09-28","date_precision":"day","short_title":"Anthropic releases Claude Sonnet 5.5","deck":"30% faster, Opus-5.5-level scores on several benchmarks at $2/$10","takeaway":"Sonnet 5.5 roughly matches the new flagship on knowledge-work and computer-use benchmarks at half the price.","category":"model-release","category_label":"Model releases","importance":4,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":10,"official":3,"filed":"2026-09-29","updated":"2026-09-29","orgs":["Anthropic"]},{"id":"2026-05-28-claude-opus-4-8","url":"https://postcutoff.com/e/2026-05-28-claude-opus-4-8/","date":"2026-05-28","date_precision":"day","short_title":"Anthropic releases Claude Opus 4.8 with cheaper fast mode and Claude Code \"dynamic workflows\"","deck":null,"takeaway":"Opus 4.8 was the last Opus 4.x release and a bridge to the Mythos-class releases in June.","category":"model-release","category_label":"Model releases","importance":3,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":7,"official":2,"filed":"2026-09-29","updated":"2026-10-11","orgs":["Anthropic"]}],"people":[],"posts":[],"videos":[{"id":"yt-mo-bitar-i-m-freaking-out-about-sonnet-5","title":"I’m freaking out about Sonnet 5","url":"https://postcutoff.com/v/yt-mo-bitar-i-m-freaking-out-about-sonnet-5/"},{"id":"yt-worldofai-claude-sonnet-5-greatest-ai-coding-model","title":"Claude Sonnet 5: Greatest AI Coding Model Ever! 1M Context, Cheap, & More! (Early Test)","url":"https://postcutoff.com/v/yt-worldofai-claude-sonnet-5-greatest-ai-coding-model/"},{"id":"yt-alex-finn-claude-sonnet-5-just-dropped-i-m-changin","title":"Claude Sonnet 5 just dropped. I'm changing how I use AI...","url":"https://postcutoff.com/v/yt-alex-finn-claude-sonnet-5-just-dropped-i-m-changin/"},{"id":"yt-ai-foundations-new-claude-sonnet-5-vs-opus-4-8-full-rev","title":"NEW Claude Sonnet 5 vs Opus 4.8! (Full Review)","url":"https://postcutoff.com/v/yt-ai-foundations-new-claude-sonnet-5-vs-opus-4-8-full-rev/"},{"id":"yt-bijan-bowen-claude-sonnet-5-is-here-hands-on-with-an","title":"Claude Sonnet 5 Is HERE – Hands-On With Anthropic’s NEW Model!","url":"https://postcutoff.com/v/yt-bijan-bowen-claude-sonnet-5-is-here-hands-on-with-an/"},{"id":"yt-worldofai-claude-sonnet-5-is-out-its-horrible-wors","title":"Claude Sonnet 5 IS OUT & ITS HORRIBLE! Worst Model By Anthropic EVER? (Fully Tested)","url":"https://postcutoff.com/v/yt-worldofai-claude-sonnet-5-is-out-its-horrible-wors/"},{"id":"yt-productive-dude-claude-sonnet-5-just-dropped-i-have-to-b","title":"Claude Sonnet 5 Just Dropped (I have to be honest...)","url":"https://postcutoff.com/v/yt-productive-dude-claude-sonnet-5-just-dropped-i-have-to-b/"},{"id":"yt-ai-coding-daily-i-tested-new-sonnet-5-with-25-coding-pro","title":"I Tested NEW Sonnet 5 with 25 Coding Prompts","url":"https://postcutoff.com/v/yt-ai-coding-daily-i-tested-new-sonnet-5-with-25-coding-pro/"}],"models":[],"changes":[{"date":"2026-09-29","type":"filed","text":"Created"}],"provenance":{"agents":[{"model":"Claude Opus 5.5","maker":"Anthropic","tool":"Claude Code"}],"filed":"2026-09-29","run":null,"sources_read":null,"updated":"2026-09-29","human_review":null,"version":{"date":"2026-10-04"}},"gaps":[{"model_id":"gpt-6-astra","name":"GPT-6 Astra","cutoff":"2026-04","days_after":61,"in_training_data":false},{"model_id":"claude-opus-5-5","name":"Claude Opus 5.5","cutoff":"2026-06","days_after":null,"in_training_data":true},{"model_id":"gemini-4-hydrogen","name":"Gemini 4 Hydrogen","cutoff":"2026-03","days_after":91,"in_training_data":false},{"model_id":"grok-4-7","name":"Grok 4.7","cutoff":"2026-05","days_after":30,"in_training_data":false}],"short_url":null}