agentskills.io specification (the open skills standard)
The open, cross-vendor specification that formalizes agent-skills as a portable format. Per adk-agents-with-skills, skills authored to this spec are universal — the same skill runs across “Gemini CLI, Claude Code, Cursor, and 40+ other products.” This is the agent-skills form factor maturing from each tool’s native skill directory into a single shared standard.
A skill’s shape
Each skill bundles: metadata (name, description), a detailed instruction body, and optional reference resources.
Progressive disclosure (the core mechanism)
A three-level loading architecture so the agent pays context cost only for what it actually uses:
- L1 — metadata (~100 tokens): names + descriptions, loaded at startup so the agent knows what exists.
- L2 — instructions (<5,000 tokens): the full skill body, loaded only when the skill is activated.
- L3 — resources: external references, loaded on demand.
The claim: this cuts baseline context usage by ~90% vs. a monolithic system prompt adk-agents-with-skills. (Vendor-stated figure, not independently benchmarked here.)
Why it matters to the thesis
It sharpens the agent-skills insight — capability as portable markdown an agent loads — into an interoperable one: the same markdown procedure now moves across vendors. It also operationalizes the “load knowledge on demand” idea that distinguishes the llm-wiki‘s index-then-drill pattern; progressive disclosure is the procedural analog of the wiki’s index → page drill-down. Related substrate: model-context-protocol.
Distribution (skills as packages)
As the format standardizes, skills get published/installed like packages — e.g. node-js-functional-patterns-skill via an MCP/skills marketplace, and Hermes’ “Skills Hub” (hermes-agent). A nascent skill-marketplace layer riding on this spec.
Canonical first-party home
Anthropic publishes the spec and a reference set of skills in its official anthropic-skills repo —
the spec (./spec/), a template, example skills, and a Claude Code plugin marketplace in one place. So
the standard isn’t only a third-party agreement; a major vendor authors and ships it directly, including
the source-available document skills that power Claude’s production file handling.
Related
agent-skills · adk · adk-agents-with-skills · model-context-protocol · llm-wiki · node-js-functional-patterns-skill · anthropic-skills
Linked from
- index
- log
- synthesis
- adk-agents-with-skills
- a2a-protocol
- adk
- agent-kanban
- agentic-coding-harness
- agentic-tooling
- agents-md
- agents-that-build-agents-ms
- anthropic-skills
- ai-job-search
- awesome-hermes-usecases
- claude-skills-ppc
- hermes-agent
- hermes-profile-builder
- langchain
- microsoft
- node-js-functional-patterns-skill
- pm-skills
- renwei-writing