OpenEnv is a framework for creating, deploying, and using isolated execution environments through simple APIs modeled on Gymnasium. It is intended for researchers and developers training agents with reinforcement learning, as well as creators who need secure environments that can be deployed and accessed through familiar protocols. The catalogue add-ons provide agent integrations and workflows for using OpenEnv.
Borrowing it
Nothing to install: this file belongs to huggingface/OpenEnv. 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/huggingface/OpenEnv/main/AGENTS.mdgit clone --depth 1 https://github.com/huggingface/OpenEnvWrote 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/huggingface/openenv/agents-md)<a href="https://agentmods.dev/instructions/huggingface/openenv/agents-md"><img src="https://agentmods.dev/badge/instructions/huggingface/openenv/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/huggingface/openenv/agents-md"><img src="https://agentmods.dev/badge/instructions/huggingface/openenv/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 | $0.00730 | $0.00730 |
| Opus 5.5 | $0.00292 | $0.00292 |
| Sonnet 5.5 | $0.00146 | $0.00146 |
| Haiku 4.5 | $0.00073 | $0.00073 |
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 1mo 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 — 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.
- 1mo ago Changed · -78 tokens per session 7840ae1a168a
- 1mo ago 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 (2,739 stars, last pushed 8d ago), licensed BSD-3-Clause. It adds 730 tokens to every session, about $0.0029 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
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).
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.