Core concepts¶

Skill¶

A directory containing at least a SKILL.md file conforming to the Agent Skills specification. A skill defines instructions, metadata, and optionally scripts, references, and assets.

Resources¶

A skill may bundle supporting files alongside SKILL.md:

• Scripts — executable scripts in a scripts/ directory.
• References — reference documents in a references/ directory.
• Assets — binary or media files in an assets/ directory.

Resources are validated during installation: they must not escape the skill directory (no path traversal).

Managed metadata¶

When skilly installs a skill, it writes a .skilly.toml file inside the skill directory. This file records the origin, source URL, version, and installation timestamp so skilly can detect updates and track provenance.

Origins¶

skilly tracks where each installed skill came from:

• GitHub — downloaded from a GitHub repository URL.
• SkillsMP — installed via the SkillsMP registry.
• Dependency — discovered via scan from a Python, Node, or Maven dependency.
• Local — created locally with skilly create.

Statuses¶

When scanning or listing skills, each skill has one of these statuses:

• installable — discovered but not yet installed.
• installed — present and up to date.
• updatable — installed but a newer version is available.

Destinations¶

skilly can install skills into several agent-specific directories:

When no flag is given, skilly uses the SKILLY_DEFAULT_DIRECTORY environment variable or falls back to .agents/skills.