Borrowing it
Nothing to install: this file belongs to sam-mountainman/codex-mcp. 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/sam-mountainman/codex-mcp/main/AGENTS.mdgit clone --depth 1 https://github.com/sam-mountainman/codex-mcpWrote 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/sam-mountainman/codex-mcp/agents-md)<a href="https://agentmods.dev/instructions/sam-mountainman/codex-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/sam-mountainman/codex-mcp/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/sam-mountainman/codex-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/sam-mountainman/codex-mcp/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 | $0.00397 | $0.00397 |
| Opus 5.5 | $0.00159 | $0.00159 |
| Sonnet 5.5 | $0.00079 | $0.00079 |
| Haiku 4.5 | $0.00040 | $0.00040 |
Grade A, and why
codex-mcp 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.
What it actually says
codex-mcp setup contract
If a user asks an AI coding agent to set up this repository, complete the setup for Claude Code instead of stopping at a README summary.
- Read the current default branch and release metadata when the repository is hosted remotely. Do not choose a version from a stale local cache.
- Confirm Node.js 18+ is available.
- Install the official Codex CLI (
@openai/codex) and Claude Code (@anthropic-ai/claude-code) only when missing. - Before changing authentication, use a structured question UI when available. Present these choices in order:
- ChatGPT account login (recommended): run
codex loginand use the user's ChatGPT/Codex allowance. - OpenAI API key: use metered OpenAI Platform billing and pass the key through stdin, never a command argument or normal chat.
- Existing authentication: preserve a working
codex login statussession.
- ChatGPT account login (recommended): run
- Run the platform installer:
- macOS/Linux:
./install.sh - Windows PowerShell:
.\install.ps1
- macOS/Linux:
- Require
npm run verify,claude plugin validate --strict ., andclaude mcp listto succeed forplugin:codex-mcp:codex. - Unless the user opts out, run
npm run live-smoke. This makes two small model calls and verifies both a new session and continuation with a changed reasoning level. - Tell the user to restart Claude Code or run
/reload-plugins, then askCodexの状態を確認して.
Do not hard-code the user's requested model or reasoning level into source. The server default is gpt-5.6-sol with max, while every model tool accepts per-call model and reasoning_effort overrides. Preserve explicit user choices exactly and let the local Codex CLI validate model availability.
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.
- 2mo ago First seen · 20 lines · 397 tokens per session scan A e97a751429ac
codex-mcp AGENTS.md is an instructions file published in the GitHub repository sam-mountainman/codex-mcp (0 stars, last pushed 8d ago), licensed MIT. It adds 397 tokens to every session, about $0.0016 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.
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