Migrates .NET projects from Newtonsoft.Json to System.Text.Json. Use when user wants to replace Newtonsoft.Json, switch to System.Text.Json, migrate JSON library, or modernize JSON serialization.
Install
npx skills add microsoft/upgrade-agent-plugins --skill newtonsoft-json-migrationnpx skills add microsoft/upgrade-agent-plugins --skill newtonsoft-json-migration -a claude-code -gnpx skills add microsoft/upgrade-agent-plugins --skill newtonsoft-json-migration -a codex -ggemini skills install https://github.com/microsoft/upgrade-agent-plugins.git --path plugins/upgrade-agent/upgrade/dotnet/skills/scenarios/newtonsoft-json-migrationgh skill install microsoft/upgrade-agent-plugins newtonsoft-json-migrationgit clone --depth 1 https://github.com/microsoft/upgrade-agent-plugins /tmp/microsoft__upgrade-agent-plugins
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/microsoft__upgrade-agent-plugins/plugins/upgrade-agent/upgrade/dotnet/skills/scenarios/newtonsoft-json-migration ~/.claude/skills/newtonsoft-json-migration # Claude Code
cp -R /tmp/microsoft__upgrade-agent-plugins/plugins/upgrade-agent/upgrade/dotnet/skills/scenarios/newtonsoft-json-migration ~/.agents/skills/newtonsoft-json-migration # Codex, Cursor, Gemini CLI, Copilot, OpenCode