Definition
Agent Skills are an extension mechanism that packages instructions, scripts and related resources into folders — typically a directory containing a SKILL.md file — so an agent can load the right capability on demand instead of keeping every instruction resident in its context.
How it works
The agent first sees only a skill’s name and description. When it judges that a skill matches the current task, it reads the full instructions and accompanying files from the skill’s folder. This progressive loading lets one agent carry a large body of domain knowledge while keeping its context lightweight.
Usage
Skills are a natural home for reusable expertise and procedures: generating documents that follow a house style, processing data in a specific format, or encoding a fixed sequence of steps for an analysis report. Skills are written by teams or communities, and one well-written skill can be reused across many tasks.
Related and confusable terms
A skill is a capability package that an agent loads, whereas the agent harness is the underlying software that hosts those capabilities and drives the run loop. A person’s frequently used skill collection often becomes part of a personal agent.