5 Agent Skills I’d install before starting any new agent project in 2026

Your coding agent can write code, refactor functions, and debug errors. But can it design production-grade prompts? Build MCP servers that follow best practices? Evaluate whether your agent's outputs are actually good? Agent Skills give your coding assistant specialized expertise on demand. They're folders containing a SKILL.md file with instructions, workflows, and references that your agent loads only when relevant. No context bloat, no manual setup. For a deep dive into how skills work and how to build your own, see How to Build and Deploy an Agent Skill from Scratch . Here are 5 skills that cover the full agent development lifecycle, from designing prompts to evaluating outputs. Every skill listed works across Claude Code, Cursor, VS Code Copilot, Codex, and Gemini CLI. To install any skill, run: npx skills add <owner/repo> --skill <skill-name> 1. prompt-engineer An expert prompt engineering skill that teaches your agent advanced techniques for designing effective LLM prompts. It c