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 skills/huggingface/openenv/implementnpx skills add huggingface/OpenEnv --skill implementgit 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 | $0.00015 | $0.00623 |
| Opus 5 | $0.00008 | $0.00311 |
| Sonnet 5 | $0.00003 | $0.00125 |
| Haiku 4.5 | $0.00002 | $0.00062 |
Grade A, and why
implement 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 — 101 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/implement
Make failing tests pass with minimal code.
Usage
/implement
The implementer will automatically find failing tests from the most recent /write-tests run.
When to Use
- After
/write-testshas created failing tests - When you have specific tests that need implementation
- Never before tests exist
When NOT to Use
- No failing tests exist (run
/write-testsfirst) - You want to add features not covered by tests
- You want to refactor (use
/simplifyinstead)
What It Does
- Finds the failing tests from
/write-tests - Reads tests to understand requirements
- Writes the minimum code to make tests pass
- Runs tests after each change
- Stops when ALL tests pass
Output
The implementer agent will produce:
## Implementation Complete
### Tests Passed
- `test_client_reset_returns_observation` ✓
- `test_client_step_advances_state` ✓
- `test_client_handles_invalid_action` ✓
### Changes Made
| File | Change |
|------|--------|
| `src/openenv/core/client.py` | Added `reset()` method |
| `src/openenv/core/client.py` | Added `step()` method |
| `src/openenv/core/client.py` | Added input validation |
### Verification
PYTHONPATH=src:envs uv run pytest tests/test_client.py -v All 3 tests passed
### Next Steps
- Mark todo as complete
- Consider `/simplify` if change was large
- Move to next pending todo
Rules
- Read the failing tests first to understand exactly what's needed
- Write the MINIMUM code needed to pass tests
- Run tests after each change to verify progress
- Do NOT add extra features not covered by tests
- Do NOT refactor existing code (that's
/simplify's job) - Stop when all tests pass
Anti-patterns (NEVER do these)
- Adding features not covered by tests
- Refactoring existing code
- Writing additional tests (that's
/write-tests's job) - Over-engineering solutions
- Adding comments or documentation beyond what's necessary
- "Improving" code that already works
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 First seen · 101 lines · 15 tokens per session scan A 825d870b8fd3
implement is a skill published in the GitHub repository huggingface/OpenEnv (2,531 stars, last pushed 3d ago), licensed BSD-3-Clause. It adds 15 tokens to every session and 623 once invoked, about $0.0001 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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