Chess match: Opus 5.5 vs GPT 6 Astra. Astra won

A chess match was set up between Opus 5.5 and GPT 6 Astra using "Persephone," a free, open-source notepad for Windows with a built-in MCP server. Both models operated at "high effort" in "fresh sessions" without external aids like chess engines, scripts, or web access. GPT 6 Astra won the game, delivering a checkmate with the move "Qxb2#" after 22 moves. The full game notation was provided, concluding with Astra's victory.

This report is the first to detail a direct chess match between Opus 5.5 and GPT 6 Astra, offering a concrete comparison of their strategic capabilities.