{"slug": "field-notes-week-of-september-21-2026", "title": "Field notes — week of September 21, 2026", "summary": "Anthropic introduced Claude Opus 5.5 on Sept 22, 2026, a flagship model it says performs at the level of Claude Fable 5.1 on most work while costing 40% less to run than Opus 5 at default settings. OpenAI released the reasoning models GPT-6 Sol and GPT-6 Luna the same day through its Responses and Chat Completions APIs, priced at $2/$0.20/$10 and $0.10/$0.01/$0.50 per million input, cached-input and output tokens respectively. DeepL also became available inside Microsoft Copilot, ChatGPT and Claude on Sept 22 via a Model Context Protocol integration that applies a company's glossary and style rules without leaving the assistant.", "body_md": "# Field notes — week of September 21, 2026\n\nWhat changed in AI-support and AI-localization tooling this week. Every item was checked against its source before it entered this list.\n\n- **Anthropic** -[introduced Claude Opus 5.5](https://www.anthropic.com/news/claude-opus-5-5) (Sept 22), a new flagship model that Anthropic says performs at the level of Claude Fable 5.1 on most work while costing 40% less to run than Opus 5 at default settings.\n\n- **OpenAI** - released[GPT-6 Sol and GPT-6 Luna](https://developers.openai.com/api/docs/changelog) (Sept 22), two new reasoning models available through the Responses and Chat Completions APIs; pricing is $2 / $0.20 / $10 per million input / cached-input / output tokens for Sol and $0.10 / $0.01 / $0.50 for Luna.\n\n- **Sierra** - published[Your agent, laid bare](https://sierra.ai/blog/your-agent-laid-bare-and-why-it-matters) (Sept 22), arguing for agent platforms that expose their logic and keep a complete, exportable record of agent actions rather than acting as an opaque black box.\n\n- **Decagon** - is[expanding into the Benelux region](https://decagon.ai/blog/growing-in-benelux) (Sept 21), building a local team across Belgium, the Netherlands and Luxembourg; the post cites Rituals, an Amsterdam beauty brand, deploying Decagon's \"Ray\" concierge across 19 countries and 15 languages within two months, handling up to 9,000 customer cases a day at peak.\n\n- **Intercom** - two changes this week:[custom metrics in reporting](https://www.intercom.com/changes/en/158136-build-the-metric-you-need-across-your-full-history) (Sept 23) let teams combine built-in measurements and filters into their own metrics;[call termination reasons](https://www.intercom.com/changes/en/157743-see-why-an-outbound-call-didn-t-connect) (Sept 21) now show why an outbound call failed to connect.\n\n- **DeepL** -[is now available inside Microsoft Copilot, ChatGPT and Claude](https://www.deepl.com/en/blog/deepl-available-in-microsoft-copilot-chatgpt-claude-mcp) (Sept 22) through a Model Context Protocol integration that translates text and documents and applies a company's glossary and style rules without leaving the assistant.", "url": "https://wpnews.pro/news/field-notes-week-of-september-21-2026", "canonical_source": "https://amitkvint.com/field-notes/2026-09-28/", "published_at": "2026-09-28 00:00:00+00:00", "updated_at": "2026-09-28 05:16:26.613297+00:00", "lang": "en", "topics": ["artificial-intelligence", "large-language-models", "ai-products", "agent-protocols", "ai-tools"], "entities": ["Anthropic", "Claude Opus 5.5", "Claude Fable 5.1", "OpenAI", "GPT-6 Sol", "GPT-6 Luna", "DeepL", "Microsoft Copilot"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/field-notes-week-of-september-21-2026", "markdown": "https://wpnews.pro/news/field-notes-week-of-september-21-2026.md", "text": "https://wpnews.pro/news/field-notes-week-of-september-21-2026.txt", "jsonld": "https://wpnews.pro/news/field-notes-week-of-september-21-2026.jsonld"}}