The apply_file_diffs tool now includes a required "summary" field so the model provides a brief description of edits. This surfaces as the title on the diff panel instead of showing only +/- line counts. Also propagates is_error from tool result content back to the model so it can distinguish failed tool calls from successful ones. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>