Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add Notysoty/openagentskills --skill agent-context-file-writergit clone --depth 1 https://github.com/Notysoty/openagentskillsWrote 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.
[](https://agentmods.dev/skills/notysoty/openagentskills/agent-context-file-writer)<a href="https://agentmods.dev/skills/notysoty/openagentskills/agent-context-file-writer"><img src="https://agentmods.dev/badge/skills/notysoty/openagentskills/agent-context-file-writer/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.
<a href="https://agentmods.dev/skills/notysoty/openagentskills/agent-context-file-writer"><img src="https://agentmods.dev/badge/skills/notysoty/openagentskills/agent-context-file-writer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00045 | $0.01692 |
| Opus 5 | $0.00023 | $0.00846 |
| Sonnet 5 | $0.00009 | $0.00338 |
| Haiku 4.5 | $0.00005 | $0.00169 |
Grade A, and why
Agent Context File Writer 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 189 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Agent Context File Writer
What this skill does
This skill writes the context file that tells a coding agent how to work in your project — CLAUDE.md for Claude Code, .cursorrules for Cursor, .windsurfrules for Windsurf, or .codebuddy for others. A well-written context file is the highest-leverage thing you can do to improve agent quality. It prevents the agent from making wrong assumptions, using the wrong patterns, or re-explaining things you've already decided.
How to use
Claude Code / Cline
Copy this file to .agents/skills/agent-context-file-writer/SKILL.md in your project root.
Then ask:
- "Use the Agent Context File Writer to create a CLAUDE.md for this project."
- "Write a .cursorrules file for our Next.js + Prisma + tRPC codebase."
Provide:
- Tech stack (framework, language, key libraries)
- Project type (API, frontend app, CLI tool, etc.)
- Any strong conventions (naming, file structure, testing approach)
- Anything agents have done wrong in the past
Cursor / Codex
Describe your project and provide any existing README or architecture notes alongside these instructions.
The Prompt / Instructions for the Agent
When asked to write an agent context file, explore the codebase first, then produce the file with all of these sections:
Step 1 — Explore the codebase
Before writing, read:
package.json/pyproject.toml/go.mod— to identify the stack- Directory structure (top 2 levels) — to understand layout
- One or two key files — to understand coding style
- Existing README — for project purpose
Step 2 — Produce the context file
The file must contain all of these sections:
Section 1: Project overview (3–5 sentences)
What the project does, who uses it, and what matters most about it. Not a marketing pitch — a technical brief for an agent.
## Project Overview
SimplyUtils is a multi-tool web app with 72+ browser-based utilities built on React + Express + PostgreSQL.
Most tools run entirely client-side for privacy. The project is deployed on Vercel (frontend) + EC2 (API).
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.
- 10d ago First seen · 189 lines · 45 tokens per session scan A ce4dc067dfdd
Agent Context File Writer is a skill published in the GitHub repository Notysoty/openagentskills (9 stars, last pushed 26d ago), licensed MIT. It adds 45 tokens to every session and 1,692 once invoked, about $0.0002 per session on Opus 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 2026-08-31.
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