An open, cross-tool format documented at agentskills.io in which a skill directory bundles an entry instructions file with its supporting resources, so any compliant agent can discover and run the skill.
How it works
The standard fixes a portable layout: a skill is a directory whose entry file carries metadata plus instructions, with its supporting resources bundled alongside. A compliant agent reads that layout to discover and load the skill, so the format is the contract rather than any one tool implementation. Adoption is what closes the loop: a directory written against the spec is portable only to the agents that already read the spec the same way.
Why it matters
A shared layout means a skill is authored once and reused wherever a compliant agent runs, rather than rebuilt per tool. The trade-off is that compliance is uneven: the spec declares what a skill is but does not enforce what any one agent must do with it, so partial adherence can be worse than no adherence for authors. A skill that works under one implementation may degrade or fail against another that names itself compliant. Portability holds as a promise pending evidence, not as a guarantee written into the standard.
In practice
A skill directory authored against the standard runs under one compliant agent without changes; the second agent that claims compliance loads the entry file but ignores a primitive the first agent honored, so the same directory degrades silently rather than fails loudly. Authors learn the portability boundary by hitting it.
Related standards and prior art
- Agent Skills standard · continuously updated defines a portable skill-directory format
- Claude Code: skills · continuously updated Claude Code implements the cross-tool standard
- F5: Agent Skills, an emerging open standard · 2026-04-06 independent editorial (Lori Mac Vittie, F5 Distinguished Engineer) naming the declaration-vs-enforcement gap the spec does not close
Defined by Ready Solutions AI