Three parallel trees documented the same ecosystem: omp-docs/skills/
(two overview pages), tools/npx-skills/ (10 pi-era npm pages), and
tools/vercel-labs-skills/ (11 CLI pages), plus a fourth leaderboard page
at engineering/skills-ecosystem.md. Verbatim overlap (identical SKILL.md
field tables in skills-spec.md vs skill-format.md; 13-agent vs 68-agent
copies of the same upstream table). Consolidated to four concept pages:
- skills/agent-skills.md: standard, format, loading, authoring (merges
skills-spec, skill-format, skill-file-structure, skill-loading,
best-practices, skills-vs-extensions)
- skills/skills-cli.md: CLI reference (merges commands, source-formats,
installation-scope, skill-discovery, lock-file, env-variables,
agent-support, related-links)
- skills/store-wiring.md: moved, fleet ops, links retargeted
- skills/ecosystem.md: replaces skills-ecosystem.md; stale 2026-08-12
top-50 table dropped, replaced with a live top-10 re-queried from the
skills.sh API tonight and the API contract re-verified (zero-based,
200/page, {skills,total,hasMore,page}, total 9909)
All facts re-verified 2026-10-19 against primary sources:
agentskills.io, vercel-labs/skills README + src/cli.ts (command set,
--full-depth) + src/skill-lock.ts (v3 lock, XDG path, wipe-on-old),
live skills.sh API. Deleted superseded core/index-doc.md (old pi-era
docs index). Retargeted all inbound links (tools/index, engineering x3,
packages x3, pi/skills, core/index). Pi-era npm skill packaging is
listed as archived under /pi/.
Refs #29
4.0 KiB
type, title, description, tags, timestamp
| type | title | description | tags | timestamp | |||||
|---|---|---|---|---|---|---|---|---|---|
| reference | Agent Instruction Files and Agent Skills | Best practices for AGENTS.md, CLAUDE.md, SYSTEM.md, and the Agent Skills SKILL.md standard. |
|
2026-08-11 |
verified: 2026-08-28
Agent Instruction Files and Agent Skills
This page explains the files that control how an AI coding agent works in a project. Use it when you create or review agent behavior configuration.
AGENTS.md
AGENTS.md is the open, cross-tool format for coding-agent instructions. The Agentic AI Foundation (under the Linux Foundation) stewards it. Over 20 coding agents support it, including Cursor, Codex, and Claude Code.
The format is plain Markdown. It has no required fields. Any heading structure works. Agents read the nearest AGENTS.md in the directory tree. In a monorepo, the agent uses a nested AGENTS.md per package.
Include these sections in an AGENTS.md:
- Project overview.
- Setup and build commands.
- Code style guidelines.
- Testing instructions.
- Pull request instructions.
- Security considerations.
- Deployment steps.
- Commit message conventions.
Agents load content progressively. Put a short summary at the top. Put detailed instructions in later sections.
CLAUDE.md
CLAUDE.md is Anthropic's tool-specific instruction file. Claude Code reads CLAUDE.md by default, not AGENTS.md. Files load in this order:
- Managed policy (
/etc/claude-code/CLAUDE.md). - User scope (
~/.claude/CLAUDE.md). - Project scope (
./CLAUDE.md). - Local scope (
./CLAUDE.local.md).
Keep each file under 200 lines. Use the @path/to/file syntax to import other files. Use path-scoped rules in .claude/rules/*.md with paths frontmatter for directory-specific rules.
To make a repository work in both AGENTS.md and CLAUDE.md workflows, create a CLAUDE.md that imports AGENTS.md with the @AGENTS.md syntax, or use a symlink.
SYSTEM.md
SYSTEM.md sets the system-level role and behavior for an agent. It establishes the persona, the prime directive, and the binding rules. In the pi-era setup, /home/dank/.pi/agent/SYSTEM.md defined the Comrade Chief Designer persona and the ASD-STE100 voice rules; the live equivalent is ~/.omp/agent/APPEND_SYSTEM.md.
Use SYSTEM.md for stable, cross-project rules. Use AGENTS.md for project-specific context. Do not duplicate content between them. Keep the division of labor clear.
Agent Skills Standard
An agent skill is a directory that contains a SKILL.md file. Skills extend an agent's capabilities. The open standard lives at agentskills.io. Over 50 agents support it.
The SKILL.md frontmatter includes these fields:
---
name: my-skill
description: What this skill does
license: MIT
compatibility: node>=18
metadata:
internal: false
---
The name field is required and must use lowercase alphanumeric plus hyphens. The description field is required. Keep the name under 64 characters. Keep the description under 1024 characters.
Skills use progressive disclosure in three stages:
- Discovery: the agent loads only the name and description at startup.
- Activation: the agent reads the full
SKILL.mdwhen a task matches. - Execution: the agent follows the instructions and reads resources on demand.
This keeps the context footprint small.
Distribution
Distribute skills through npm packages with a pi manifest, or through the skills CLI from Vercel Labs. See the Skills Documentation pages for details.
Citations
- agents.md
- OpenAI Agentic AI Foundation (unverified — returned 403)
- Claude Code memory documentation
- Agent Skills standard
- agentskills/agentskills
- vercel-labs/skills