Definition
Plain language
A documentation file an AI agent can consult at runtime to do a task better, like an employee handbook it may or may not open.
As stated in the literature
A markdown instruction document with trigger conditions and procedural guidance that an LLM agent loads at its own discretion; acts as a guidance prior over agent behavior rather than executable code, so failures can stem from bad instructions or from the agent ignoring good ones.
Also called: skill
Why it matters: It lets an agent improve at specialized tasks by reading guidance at runtime, but success depends on whether the agent actually consults and follows that guidance.
For example, an AI agent about to format a spreadsheet can open a skill file that explains the company's preferred layout before it starts editing.
Heard on the show
“It's attacker skill times defender fragility.”Episode 202 — How Do You Know an AI Agent Actually Refused? Check the World, Not the Words