How to secure local tool execution in OpenClaw using OPA/Rego policies

OpenClaw is an incredible, local-first personal AI assistant. Because it is designed to run directly on your machine, you can give it access to local files, databases, and terminal commands to write and execute code. However, this tool-calling autonomy introduces severe security risks. If your agent is exposed to malicious data or suffers from prompt injection, a compromised agent could execute a destructive command (like modifying your host filesystem or running an unapproved shell script). To secure this without modifying OpenClaw’s core code, you can route its tool-calling pipeline through a policy firewall. Here is how you can use Loopers (an open-source Go proxy) to intercept Model Context Protocol (MCP) tool calls and validate them against Open Policy Agent (OPA/Rego) rules before they can execute on your host machine. 1. Intercepting the Tool Call Loopers acts as a local proxy. By pointing OpenClaw’s tool-calling pipeline to the Loopers proxy address, all JSON-RPC 2.0 tools/call requests are routed through the proxy first. 2. Writing the Security Policy (Rego) You can define fine-grained security rules in a local .rego file (e.g., /policies/security.rego). Loopers compiles and evaluates this on the critical path in less than a millisecond: regopackage loopers.policy default allow = false # 1. Allow the request by default if no deny rules match allow { not deny } # 2. Block OpenClaw from executing terminal shell tools in development deny[msg] { input.request.method == "mcp_tool_call" input.request.tool_name == "execute_shell_command" input.agent.tags.environment == "development" msg := "Terminal command execution is blocked in local development." } # 3. Restrict sensitive filesystem tools to admin owners only deny[msg] { input.request.tool_name == "delete_file" input.agent.owner != "admin" msg := sprintf("File deletion restricted. Current owner is: %s", [input.agent.owner]) } 3. Execution & Blocking When OpenClaw attempts to run a tool: The proxy intercepts the JSON-RPC request and extracts the metadata (tool name, MCP server, agent tags, and owner name). It evaluates the Rego rules. If a deny rule matches, the proxy drops the connection immediately and returns a 403 Forbidden response, preventing the shell command or filesystem write from ever hitting your system. By separating the agent's execution layer from your security policies, you guarantee that even a compromised agent cannot bypass your guardrails. We need the community's support! Loopers is fully open-source (MIT licensed) and self-hosted. As we launch, we need your help to make Agent Runtime Governance a standard: Star the repo: If you find this project or the concept of OPA-based agent governance useful, a star on GitHub goes a long way in helping us get visibility. Repo in comments. Contribute: We are actively looking for contributors to help us write more framework integrations and client SDK adapters. How are you currently securing OpenClaw and other local-first agents in your workflows? Are you sandboxing the entire host namespace, or using proxy-level policies? Let's discuss!