Agent Skill
A packaged set of instructions, reference files, templates, or scripts that an agent can load on demand for a specific capability (often via an open Agent Skills standard).
Plain English
It is a reusable playbook the agent pulls in only when the task matches.
Example
A `security-review` skill tells the agent what files to inspect, which checks to run, and how to report findings.
Why it matters
Skills keep specialized knowledge out of the main prompt until needed, which helps reliability and context size across Cursor, Claude Code, Codex, and similar tools.