Universal SKILL.md Cross-Agent Format: One File Runs Across Claude Code, Cursor, Gemini CLI, Codex CLI, and Antigravity IDE

Anthropic·medium signal

The Claude Code skills ecosystem has converged on a universal SKILL.md format accepted by all major coding agents as of March 2026. Anthropic's official frontend-design skill (277K+ installs) demonstrates the pattern: a single SKILL.md file injected before any code generation that encodes design philosophy, typography preferences, and color system rules. Because the same file runs across five IDEs, investing in a well-crafted SKILL.md for your project produces consistent output regardless of which coding agent a team member uses.