Anthropic Skills Repository & Agent Skills Spec#
Summary#
anthropic’s official skills repository for Claude, plus the agent-skills-standard specification. Skills are folders of instructions, scripts, and resources that Claude loads dynamically. The repo contains 17 skills across creative, technical, enterprise, and document categories — including the production document skills that power Claude.ai’s file capabilities.
Key Takeaways#
- Agent Skills is an open standard: Defined at agentskills.io, not Anthropic-proprietary. Designed for cross-tool compatibility. claude-code extends it with invocation control, subagent execution, and dynamic context injection.
- Progressive disclosure is the core design principle: Metadata (~100 tokens) loaded at startup for all skills. Full instructions (<5000 tokens recommended) loaded only when activated. Resources loaded only when needed. This is how skills scale without blowing up context.
- SKILL.md is the only required file: YAML frontmatter (name + description) + markdown instructions. Optional: scripts/, references/, assets/ directories. Keep under 500 lines.
- Document skills are production code: The docx, pdf, pptx, xlsx skills power Claude.ai’s document capabilities. Source-available (not open source) — shared as reference for complex skill patterns.
- Plugin marketplace for Claude Code:
/plugin marketplace add anthropics/skillsregisters the repo. Skills installable individually. - Partner ecosystem emerging: Notion has published skills for Claude. The
allowed-toolsfield (experimental) hints at future tool-level permission control per skill.