How to Build Custom Commands for Gemini CLI and Antigravity

In the rapidly evolving world of AI CLI tools like Gemini CLI and Antigravity, the way we interact with autonomous agents is changing. Instead of writing complex, platform-specific plugins, custom commands are now officially merged with and built as Agent Skills. This means that to create a custom command (which you can trigger via a slash command like /my-command ), you simply need to create a skill using the open Agent Skills standard. Because tools like Gemini CLI and Antigravity Commands are defined by a directory containing a SKILL.md file.