The format turns procedural knowledge into a maintained asset instead of repeating it inside every prompt. The Agent Skills specification describes a folder built around a SKILL.md file, while current frameworks can expose those folders through an agent harness.
How do agent skills work?
A harness advertises each skill using a compact name and description. When a task matches, the agent loads the full instructions and any referenced resources. Progressive loading keeps unrelated procedures out of the context window, which matters when a coding agent has dozens of available workflows.
How are skills different from tools?
A tool performs an action. A skill explains how and when to use tools together. An agent may follow one skill while making several tool calls, including calls exposed through MCP. Teams should review third-party skills like code because instructions and bundled scripts can both change agent behavior. Our LangChain agent skills guide shows how that separation works in practice.