Borrowing it
Nothing to install: this file belongs to ARCASSystems/FounderOS. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/ARCASSystems/FounderOS/main/AGENTS.mdgit clone --depth 1 https://github.com/ARCASSystems/FounderOSWrote 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/instructions/arcassystems/founderos/agents-md)<a href="https://agentmods.dev/instructions/arcassystems/founderos/agents-md"><img src="https://agentmods.dev/badge/instructions/arcassystems/founderos/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.
<a href="https://agentmods.dev/instructions/arcassystems/founderos/agents-md"><img src="https://agentmods.dev/badge/instructions/arcassystems/founderos/agents-md.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 | $0.02233 | $0.02233 |
| Opus 5.5 | $0.00893 | $0.00893 |
| Sonnet 5.5 | $0.00447 | $0.00447 |
| Haiku 4.5 | $0.00223 | $0.00223 |
Grade A, and why
FounderOS 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 today.
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 — 69 lines — stays where its author put it; the contents beside it link to each section on GitHub.
FounderOS - Agent Instructions
A thin bridge for Codex, Cursor, Windsurf, Gemini, and other non-Claude agents operating in this repo.
The canonical instruction file is CLAUDE.md. It is the source of truth for how this OS behaves: what the repo is, the repo map, the six role modes (four active, two reference-until-invoked), the full skill and command lists, the brain substrate, the hooks, the wiki conventions, and what not to do. Read it in full. This file only carries the deltas a non-Claude agent needs on top of it. If anything here ever disagrees with CLAUDE.md, CLAUDE.md wins.
Read first
CLAUDE.md- the source of truth for behaviour, structure, roles, skills, commands, hooks, and substrate.README.md- the product picture and the setup path.
The skill registry is skills/index.md (97 skills, 47 commands); the long-form per-skill reference is docs/skills.md. Read those for the lists rather than expecting them duplicated here.
Cross-agent deltas (what differs from a Claude Code session)
- Slash commands are Claude Code specific. The 47 commands in
.claude/commands/cannot be run by a non-Claude agent. Treat them as documented procedures, not executable actions. - Skills are procedural reference. Each
skills/<name>/SKILL.mdhas trigger frontmatter for Claude's auto-invocation (ignore that) and a protocol body that is portable. Follow the body by hand. - You cannot run hooks, MCP tools, slash commands, or local writes unless your environment actually supports them. Do not claim that setup, hooks, file writes, MCP authentication, or scheduled routines have run. Say plainly what you can and cannot do in this environment.
- Runtime honesty and the per-skill
Runs on:contract: every skill declares its runtime class (reasoning,local-writes, orlocal-exec) on aRuns on:line in itsSKILL.md. The full contract and the honest-degradation rule live inCLAUDE.md. Read it there. If your environment can write to the folder you may run alocal-writesskill; if it cannot run a script you read the produced artifacts for alocal-execskill and say so. If anything here disagrees,CLAUDE.mdwins. - Opinions of consequence: Claude has
/founder-os:devilto run the output bias self-check. You do not. Followrules/biases.mdby hand - attach the strongest counter-case, a confidence level (high / medium / low), what evidence is absent, and the do-nothing option. Name the most likely bias and argue the other side; do not claim bias-free advice. - Do not modify the operator's data files (
core/,context/,cadence/,brain/) without explicit instruction. Claude has approval-gates and hooks guarding this; you do not, so the burden is on you to ask first. - The safety rules below are yours to carry. In Claude Code they arrive through
CLAUDE.mdevery session. Here nothing loads them for you, so they are copied into this file in full. - Empty state: if the six context files named in
CLAUDE.mdare missing, the OS is not set up. Do not invent identity, priorities, decisions, clients, or revenue. - Setup, the one truth. The setup wizard, the slash commands, the hooks and the session brief run in Claude Code. Tell the user that the supported way is to open the folder in Claude Code and say "set up Founder OS". If they want to go ahead here instead, you can follow
skills/founder-os-setup/SKILL.mdand itsreferences/by hand, one question at a time, but without the hooks, the commands or the session brief. Say plainly that this path has not been tested before you start it.
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.
- today Changed · +18 lines · +1,047 tokens per session ce8fe37eac4e
- 22d ago Changed 6a9d851b240f
- 1mo ago First seen · 51 lines · 1,186 tokens per session scan A 459561602b4e
FounderOS AGENTS.md is an instructions file published in the GitHub repository ARCASSystems/FounderOS (6 stars, last pushed yesterday), licensed MIT. It adds 2,233 tokens to every session, about $0.0089 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 2026-08-31.
Other instructions, from other repositories
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Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).
next.js AGENTS.md
AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
vscode oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, cache eligibility and rollout and applying the notice (cutover).
langchain AGENTS.md
AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
deepseek-harness AGENTS.md
AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.