Guardian MCP

Guardian MCP is a robust AI engineering gate designed to bring discipline and memory to AI code development. It tackles common issues with AI coding assistants, such as code hallucinations, the creation of duplicate functions, and the introduction of breaking changes. By implementing a unique 3-step Engineering Gates workflow—Analysis, Planning, and Execution—Guardian MCP ensures that AI tools analyze existing code, receive approval for their plans, and then implement changes in a structured, controlled manner.

How to use Guardian MCP

To use Guardian MCP, first obtain a free API Key from guardianmcp.dev. Next, install Guardian by adding it to your MCP client configuration (e.g., Claude Code, Cursor, Windsurf) using an `npx` command and setting your `GUARDIAN_API_KEY`. After restarting your AI tool, you can optionally configure AI integration with a rules file (like CLAUDE.md or .cursorrules) in your project root to automate Guardian's tool invocation. If no rules file is used, you must explicitly prompt your AI with phrases like "Use Guardian to implement this feature" to activate its capabilities. The system then guides the AI through an analysis, planning, and execution cycle, ensuring adherence to established code practices.

Core Features of Guardian MCP

• Engineering Gates Workflow: A 3-step process (Analysis → Planning → Execution) that forces AI to think, analyze existing code, and get approval before writing.
• 100% Private & Local: Code is indexed locally on your machine; no code content, file paths, or function names are ever transmitted to servers, ensuring maximum privacy and GDPR compliance.
• Universal Language Support: Supports 17 programming languages including Rust, JavaScript, TypeScript, Python, Go, Java, C, C++, C#, PHP, Ruby, Swift, Elixir, Haskell, Lua, R, and Bash, utilizing tree-sitter AST parsing.
• Prevents Duplicate Code & Hallucinations: Actively stops AI from recreating existing functions or inventing non-existent code, enforcing code reuse.
• Persistent Cross-Session Memory: Provides AI with a long-term memory of your codebase structure, API contracts, design decisions, and verified configuration values.
• Rust-Powered Speed: Offers high performance with AST parsing, capable of handling over 10,000 files in seconds and providing incremental updates.
• Semantic Code Search & Analysis: Allows AI to find similar code, references, and map dependency graphs, enhancing code understanding.
• Project Isolation: Manages multiple codebases by scoping all queries to the current project, preventing cross-contamination.

Use Cases for Guardian MCP

Guardian MCP is ideal for various development scenarios where AI coding assistants are utilized. It's invaluable when starting new features, ensuring they integrate seamlessly without introducing duplicates. It excels in refactoring legacy code by providing AI with a deep understanding of existing structures. Developers can use it to onboard AI to complex projects, build robust API integrations, and manage CLI & script projects with enhanced reliability. Furthermore, it's perfect for exploring unfamiliar codebases, preventing breaking changes, and resuming development after interruptions by maintaining persistent context and progress tracking.

Advantages of Guardian MCP

The primary advantage of Guardian MCP is its ability to significantly enhance the reliability and efficiency of AI-assisted coding. By preventing hallucinations and duplicate code, it saves developers countless hours typically spent on debugging and refactoring. Its enforced engineering gates promote a disciplined development process, leading to cleaner, more maintainable code. The local-first approach guarantees unparalleled privacy and data security, as sensitive code never leaves the developer's machine. With broad language support and Rust-powered speed, Guardian MCP offers a powerful, transparent, and trustworthy solution for modern AI-driven software development.

Pricing and Plans

Guardian MCP offers a tiered pricing structure to suit different user needs:

• Meteor: $0/month. This free-forever plan includes 200 requests per month and 1 API key, perfect for testing the platform or hobby projects.
• Comet: $9/month. This plan provides 500 requests per month and 3 API keys, designed for individual developers building 2-3 features per week.
• Supernova: $25/month. This plan offers unlimited requests and 5 API keys, built for power users and heavy usage, ensuring no rate limits or interruptions.