agent-skills: Instructions file for Codex

AGENTS.md

agent-skills AGENTS.md is an instructions file for Codex, OpenCode from callstackincubator/agent-skills. It costs 709 tokens per session, scanned A, original, MIT.

Instructions for creating and maintaining agent skills in a Markdown-based repository. An agent skill is a focused set of instructions that helps a coding assistant handle a particular task.

In plain words
What is it for?
Use it when adding or reviewing skills, writing their descriptions and instructions, organizing reference files, or validating the repository.
Why use it?
It provides the required file structure, naming rules, metadata, and validation checklist so new skills remain consistent and usable.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: mentions Claude Code.

This is callstackincubator/agent-skills's own configuration. It tells Codex and OpenCode how to work on agent-skills itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything agent-skills configures →

About the project

Callstack Agent Skills is a collection of instructions that gives AI coding assistants practical knowledge for building React Native applications. Developers use it for app development, performance, navigation, testing, CI, device automation, and migrations to React Native. The catalogue entries are the project's skills, rules, and instructions for compatible coding assistants.

callstackincubator/agent-skills · 1,702 stars · on GitHub

Reuse

Borrowing it

Nothing to install: this file belongs to callstackincubator/agent-skills. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/callstackincubator/agent-skills/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/callstackincubator/agent-skills

Made for: Codex, OpenCode.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for agent-skills AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/callstackincubator/agent-skills/agents-md/github.svg)](https://agentmods.dev/instructions/callstackincubator/agent-skills/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/callstackincubator/agent-skills/agents-md"><img src="https://agentmods.dev/badge/instructions/callstackincubator/agent-skills/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for agent-skills AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/callstackincubator/agent-skills/agents-md"><img src="https://agentmods.dev/badge/instructions/callstackincubator/agent-skills/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 709 This file is loaded in full into every session.
When invoked 709 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00709 $0.00709
Opus 5.5 $0.00284 $0.00284
Sonnet 5.5 $0.00142 $0.00142
Haiku 4.5 $0.00071 $0.00071

Measured 2mo ago against content hash 8995509d82f1, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

agent-skills AGENTS.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

AGENTS.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Skills

Markdown-only repo with agent skills for React Native and GitHub workflows. No build step.

Adding New Skills

Follow agentskills.io spec and Claude Code best practices.

Quick Checklist

  1. Create skills/<skill-name>/SKILL.md
  2. Directory name must match name field exactly
  3. Required frontmatter:
    ---
    name: skill-name          # lowercase, hyphens only, 1-64 chars
    description: Third person description of what it does. Use when [trigger conditions].
    ---
    
  4. Optional frontmatter: license, metadata (author, tags), compatibility
  5. Keep body under 500 lines
  6. Use markdown links: [file.md](references/file.md) not bare filenames
  7. Run /validate-skills to verify

What Makes a Good Skill

  • Concise: Only add context Claude doesn't already have
  • Third person description: "Processes X" not "I help with X"
  • What + When: Description says what it does AND when to use it
  • One-level deep: Reference files link from SKILL.md, not from other references
  • No redundancy: Don't repeat description content in body

Repo Structure

skills/
├── react-native-best-practices/
│   ├── SKILL.md                    # Main entry point with quick reference + problem→skill mapping
│   └── references/
│       ├── images/                 # Visual references (profiler screenshots, diagrams)
│       ├── js-*.md                 # JavaScript/React skills
│       ├── native-*.md             # iOS/Android native skills
│       └── bundle-*.md             # Bundling & app size skills
│
└── react-native-tv-best-practices/
    ├── SKILL.md                    # Main entry point with priority framework + problem→reference routing
    └── references/
        ├── focus-*.md              # Focus / D-pad navigation
        ├── nav-*.md                # Directional navigation & keyboard
        ├── design-*.md             # 10-foot design (typography, layout, color)
        ├── perf-*.md               # TV performance (lists, memory, animations)
        ├── video-*.md              # Video streaming, players, DRM
        ├── a11y-*.md               # TV accessibility
        ├── setup-*.md              # Cross-platform setup & architecture
        ├── test-*.md               # Testing strategy
        └── release-*.md            # CI/CD

Read the full file on GitHub · 72 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2mo ago First seen · 72 lines · 709 tokens per session scan A 8995509d82f1

Subscribe to this mod's changes

agent-skills AGENTS.md is an instructions file published in the GitHub repository callstackincubator/agent-skills (1,702 stars, last pushed 29d ago), licensed MIT. It adds 709 tokens to every session, about $0.0028 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

agent-skills AGENTS.md compared with instructions from other repositories

agent-skills AGENTS.md next to 6 instructions from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
agent-skills AGENTS.mdcallstackincubator/agent-skillsInstructions file1.7k29d agoMITA709Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA9,719GitHub Copilot
next.js AGENTS.mdvercel/next.jsInstructions file143ktodayMITA7,461Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchainInstructions file149kyesterdayMITA4,680Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA5,516GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA3,093GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harnessInstructions file274k2d agoMITA4,313Codex, OpenCode