llm-anthropic 0.29

Simon Willison released llm-anthropic 0.29 on 22nd September 2026, adding support for Anthropic's Claude Opus 5.5 model to the LLM command-line tool. The update lets users run prompts against the new model with the command "llm -m claude-opus-5.5". The release follows the same-day launch of Claude Opus 5.5 alongside GPT-6 Sol, GPT-6 Luna and a new price war.

22nd September 2026 Adds support for Claude Opus 5.5 https://www.anthropic.com/claude-opus-5-5 : llm -m claude-opus-5.5 "prompt goes here" Recent articles - Claude Opus 5.5, GPT-6 Sol, GPT-6 Luna, and a new price war https://simonwillison.net/2026/Sep/22/opus-and-sol-and-luna/ - 22nd September 2026 - Jev introduces a new shape of LLM - System One, aka Decision Models https://simonwillison.net/2026/Sep/21/jev/ - 21st September 2026 - Generating running routes with GPT-6 Astra and ChatGPT Work https://simonwillison.net/2026/Sep/12/astra-running-routes/ - 12th September 2026