# Buckler

> Agent gatehouse for AI coding harnesses (Cursor, Claude Code, …): declarative hook policies, harness-neutral core + adapters, YAML packs (polished Git pack by default). Cosign-signed releases; setup.sh for Linux, macOS, Windows (Git Bash).

- **Type:** MCP server
- **Install:** `agentstack add mcp-rethunk-ai-buckler`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [Rethunk-AI](https://agentstack.voostack.com/s/rethunk-ai)
- **Installs:** 0
- **Category:** [AI & ML](https://agentstack.voostack.com/c/ai-and-ml)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [Rethunk-AI](https://github.com/Rethunk-AI)
- **Source:** https://github.com/Rethunk-AI/buckler
- **Website:** https://github.com/Rethunk-AI/buckler

## Install

```sh
agentstack add mcp-rethunk-ai-buckler
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Buckler — Agent Gatehouse

> **Protect your system from unauthorized agentic actions.** Declarative, multi-harness policy engine that intercepts shell commands and tool calls from AI coding assistants—before they cause damage.

[](https://github.com/Rethunk-AI/buckler/actions/workflows/ci.yml)
[](https://python.org)
[](https://github.com/astral-sh/uv)
[](https://github.com/astral-sh/ruff)
[](https://mypy-lang.org/)
[](LICENSE)

---

## Summary

Buckler is a **harness-neutral** policy engine: declarative YAML rules evaluate normalized signals from any AI coding assistant and decide whether to **allow**, **deny**, **ask**, or **nudge**—independent of which harness fired the hook. The `agent-git` and `agent-gh` packs ship enabled by default, blocking uncontrolled `git` commits, force-pushes, remote destruction, and destructive `gh` commands out of the box.

## Feature Highlights

- **Harness-neutral core** — the evaluator knows nothing about Cursor's `hooks.json`; only thin adapters do
- **Declarative YAML packs** — rules match on abstract trigger kinds, not harness-specific strings
- **`agent-git` + `agent-gh` packs** — deny uncontrolled git commits / force-push / remote destruction; deny destructive `gh` subcommands; nudge toward MCP tools
- **Cosign-signed releases** — every release tarball is verified before install
- **Cross-platform** — Linux, macOS, Windows (Git Bash)

## Documentation

| Audience | File |
|----------|------|
| **Install, configure, bypass, troubleshoot** | [HUMANS.md](HUMANS.md) |
| **LLM / dev internals, contract rules** | [AGENTS.md](AGENTS.md) |
| **Architecture & adapter boundary** | [ARCHITECTURE.md](ARCHITECTURE.md) |
| **Commit conventions, CI, dev setup** | [CONTRIBUTING.md](CONTRIBUTING.md) |
| **Threat model, Cosign verification, disclosure** | [SECURITY.md](SECURITY.md) |
| **Troubleshooting (hooks, policy, audit log)** | [docs/troubleshooting.md](docs/troubleshooting.md) |
| Rule YAML schema | [docs/rule-schema.md](docs/rule-schema.md) |
| Default `agent-git` pack matrix | [docs/agent-git.md](docs/agent-git.md) |
| Default `agent-gh` pack matrix | [docs/agent-gh.md](docs/agent-gh.md) |
| Path resolution (XDG, Windows, env overrides) | [docs/paths.md](docs/paths.md) |

## Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [Rethunk-AI](https://github.com/Rethunk-AI)
- **Source:** [Rethunk-AI/buckler](https://github.com/Rethunk-AI/buckler)
- **License:** MIT
- **Homepage:** https://github.com/Rethunk-AI/buckler

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/mcp-rethunk-ai-buckler
- Seller: https://agentstack.voostack.com/s/rethunk-ai
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.