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 agentmods add instructions/huggingface/openenv/agents-mdgit clone --depth 1 https://github.com/huggingface/OpenEnvWhat 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 | $0.00808 | $0.00808 |
| Opus 5 | $0.00404 | $0.00404 |
| Sonnet 5 | $0.00162 | $0.00162 |
| Haiku 4.5 | $0.00081 | $0.00081 |
Grade A, and why
OpenEnv 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 yesterday.
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 — 30 lines — stays where its author put it; the contents beside it link to each section on GitHub.
AGENTS.md
See CLAUDE.md for the full agentic workflow, skills, and standard build/test/lint commands. This file adds cloud-environment specifics on top of that.
Cursor Cloud specific instructions
Project shape
OpenEnv is a Python (uv) monorepo: a core library + openenv CLI in src/openenv/, and ~35 self-contained RL "environments" under envs/ (each its own pyproject.toml/Dockerfile/openenv.yaml). There is no Node/JS, no shared database, and no single always-on backend. The product is the framework plus per-environment FastAPI servers; envs/echo_env/ is the canonical reference env.
Environment / dependencies
- The startup update script installs
uv(if missing) and runsuv sync --all-extras, which creates.venv/with all core + CLI + provider extras. You do not need to reinstall on a fresh session. uvlives at~/.local/binand is already onPATHin login shells (added to.bashrc/.profile).- Core deps are enough to run/test the core library and
echo_env. Most other envs have optional, heavy deps (torch, simulators, etc.); their tests auto-skip when deps are absent. Install per-env extras only when working on that env, e.g.uv pip install -e "envs/coding_env[dev]".
Lint / test / build / run (standard commands live in CLAUDE.md)
- Tests need
PYTHONPATH=src:envs, e.g.PYTHONPATH=src:envs uv run pytest tests/ -q. Full suite is ~80s; ~129 tests skip without optional env deps (expected). - Lint:
uv run usort check src/ tests/,uv run ruff format src/ tests/ --check,uv run ruff check src/ tests/. Note:usort checkcurrently flags two pre-existing files (tests/envs/test_grid_world.py,tests/envs/test_julia_env.py) on a clean tree — not introduced by your change.
Running an environment end-to-end (no Docker needed)
- Start a server (echo_env example):
PYTHONPATH=src:envs uv run python -m echo_env.server.app(listens on0.0.0.0:8000; health at/health). import echo_envresolves only whenenvs/is onPYTHONPATH.openenv serveis a stub that just prints instructions; run the server module (oruvicorn echo_env.server.app:app) directly instead.- Interact via the client:
EchoEnv(base_url="http://localhost:8000").sync()then.reset()/.list_tools()/.step(CallToolAction(...)).
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.
- yesterday First seen · 30 lines · 808 tokens per session scan A 915452157c9c
OpenEnv AGENTS.md is an instructions file published in the GitHub repository huggingface/OpenEnv (2,531 stars, last pushed 4d ago), licensed BSD-3-Clause. It adds 808 tokens to every session, about $0.0040 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.
Other instructions, from other repositories
vscode buildNext.instructions.md
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).
spec-kit AGENTS.md
AGENTS.md instructions for github/spec-kit, covering agents.md, about spec kit and specify, quickstart — add a new integration in 5 steps, integration architecture and integrationmanifest — file tracking.
codex AGENTS.md
AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.
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 oss-third-party-notices.instructions.md
Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, applying the notice (cutover) and fallback chain (never fail the build).
next.js AGENTS.md
Instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.