Guides stable API and interface design. Use when designing APIs, module boundaries, or any public interface. Use when creating REST or GraphQL endpoints, defining type contracts between modules, or establishing boundaries between frontend and backend.
Install
npx skills add addyosmani/agent-skills --skill api-and-interface-designnpx skills add addyosmani/agent-skills --skill api-and-interface-design -a claude-code -gnpx skills add addyosmani/agent-skills --skill api-and-interface-design -a codex -ggemini skills install https://github.com/addyosmani/agent-skills.git --path skills/api-and-interface-designgh skill install addyosmani/agent-skills api-and-interface-designgit clone --depth 1 https://github.com/addyosmani/agent-skills /tmp/addyosmani__agent-skills
mkdir -p ~/.claude/skills ~/.agents/skills
cp -R /tmp/addyosmani__agent-skills/skills/api-and-interface-design ~/.claude/skills/api-and-interface-design # Claude Code
cp -R /tmp/addyosmani__agent-skills/skills/api-and-interface-design ~/.agents/skills/api-and-interface-design # Codex, Cursor, Gemini CLI, Copilot, OpenCode