nixmcp

# MCP-NixOS - Because Your AI Shouldn't Hallucinate Package Names [](https://mcptoplist.com/server/glama%2Futensils%2Fmcp-nixos) [](https://github.com/utensils/mcp-nixos/actions/workflows/ci.yml) [](https://codecov.io/gh/utensils/mcp-nixos) [](https://pypi.org/project/mcp-nixos/) [](https://flakehub.com/flake/utensils/mcp-nixos) [](https://www.python.org/downloads/)  [](https://claude.ai) ## Quick Start **🚨 No Nix/NixOS Required!** Works on any system - Windows, macOS, Linux. You're just querying APIs. ### Option 1: uvx (Recommended) [](https://cursor.com/install-mcp?name=nixos&config=eyJjb21tYW5kIjoidXZ4IG1jcC1uaXhvcyJ9) ```json { "mcpServers": { "nixos": { "command": "uvx", "args": ["mcp-nixos"] } } } ``` ### Option 2: Nix [](https://cursor.com/install-mcp?name=nixos&config=eyJjb21tYW5kIjoibml4IHJ1biBnaXRodWI6dXRlbnNpbHMvbWNwLW5peG9zIC0tIn0%3D) ```json { "mcpServers": { "nixos": { "command": "nix", "args": ["run", "github:utensils/mcp-nixos", "--"] } } } ``` ### Option 3: Docker [](https://cursor.com/install-mcp?name=nixos&config=eyJjb21tYW5kIjoiZG9ja2VyIiwiYXJncyI6WyJydW4iLCItLXJtIiwiLWkiLCJnaGNyLmlvL3V0ZW5zaWxzL21jcC1uaXhvcyJdfQ%3D%3D) ```json { "mcpServers": { "nixos": { "command": "docker", "args": ["run", "--rm", "-i", "ghcr.io/utensils/mcp-nixos"] } } } ``` Your AI now has access to real NixOS data instead of making things up. You're welcome. ### Option 4: HTTP (Remote MCP) FastMCP supports running this server over HTTP at a URL (the MCP endpoint defaults to `/mcp`). ```bash # Run an HTTP MCP server at http://127.0.0.1:8000/mcp MCP_NIXOS_TRANSPORT=http MCP_NIXOS_HOST=127.0.0.1 MCP_NIXOS_PORT=8000 mcp-nixos ``` STDIO (default): ```bash MCP_NIXOS_TRANSPORT=stdio mcp-nixos ``` Custom path: ```bash MCP_NIXOS_TRANSPORT=http MCP_NIXOS_PATH=/api/mcp mcp-nixos ``` Stateless HTTP (disables per-client session state): ```bash MCP_NIXOS_TRANSPORT=http MCP_NIXOS_STATELESS_HTTP=1 mcp-nixos ``` ### Option 5: Pi Coding Agent [Pi](https://www.npmjs.com/package/@mariozechner/pi-coding-agent) does not speak MCP natively. Two supported paths: **A. pi-mcp-adapter (recommended — speaks MCP, single source of truth):** ```bash pi install npm:pi-mcp-adapter ``` Then add to `~/.pi/agent/mcp.json`: ```json { "mcpServers": { "nixos": { "command": "uvx", "args": ["mcp-nixos"], "lifecycle": "lazy" } } } ``` **B. Project-local extension (clone + run):** this repo ships `.pi/extensions/mcp-nixos.ts`, auto-loaded when you run `pi` in the cloned repo. Optional: `cd .pi && npm install` for editor type resolution. Pi runs it either way. ## What Is This? An MCP server providing accurate, real-time information about: - **NixOS packages** - 130K+ packages that actually exist - **NixOS options** - 23K+ ways to configure your system - **Home Manager** - 5K+ options for dotfile enthusiasts - **nix-darwin** - 1K+ macOS settings Apple doesn't document - **Nixvim** - 5K+ options for Neovim configuration via [NuschtOS search](https://github.com/NuschtOS/search) - **NVF** - 2.4K+ Neovim options from its [published unstable documentation](https://nvf.notashelf.dev/options.html) - **FlakeHub** - 600+ flakes from [FlakeHub.com](https://flakehub.com) registry - **Noogle** - 2K+ Nix functions with type signatures via [noogle.dev](https://noogle.dev) - **NixOS Wiki** - Community documentation and guides from [wiki.nixos.org](https://wiki.nixos.org) - **nix.dev** - Official Nix tutorials and guides from [nix.dev](https://nix.dev) - **Package versions** - Historical versions with commit hashes via [NixHub.io](https://www.nixhub.io) - **Binary cache status** - Check if packages are cached on cache.nixos.org with download sizes - **Local flake inputs** - Explore your pinned flake dependencies directly from the Nix store (requires Nix) ## The Tools Just two. We consolidated 17 tools into 2 because your AI's context window isn't infinite. **~1,030 tokens total.** That's it. While other MCP servers are hogging your context like it's Black Friday, we're sipping minimalist tea in the corner. Your AI gets NixOS superpowers without the bloat. ### `nix` - Unified Query Tool One tool to rule them all: ```text nix(action, query, source, type, channel, limit, version, system) ``` `version` and `system` are only used by `action="cache"`. | Action | What it does | |--------|-------------| | `search` | Search packages, options, programs, or flakes | | `info` | Get detailed info about a package or option | | `stats` | Get counts and categories | | `browse` | Browse Home Manager, Darwin, Nixvim, NVF, or Noogle by prefix (legacy alias: `options`) | | `channels` | List available NixOS channels | | `flake-inputs` | Explore local flake inputs from Nix store | | `cache` | Check binary cache status for packages | | `store` | Read files or list directories at an explicit `/nix/store` path (requires Nix) | | Source | What it queries | |--------|----------------| | `nixos` | Packages, options, programs | | `home-manager` | Home Manager options | | `darwin` | nix-darwin options | | `flakes` | Community flakes (search.nixos.org) | | `flakehub` | FlakeHub registry (flakehub.com) | | `nixvim` | Nixvim Neovim configuration options | | `nvf` | NVF Neovim configuration options (latest unstable docs) | | `noogle` | Nix function signatures and docs (noogle.dev) | | `wiki` | NixOS Wiki articles (wiki.nixos.org) | | `nix-dev` | Official Nix documentation (nix.dev) | | `nixhub` | Package metadata and store paths (nixhub.io) | NVF results use canonical `vim.*` option paths. Queries may also use the shorthand `programs.nvf.vim.*` or the NixOS/Home Manager module path `programs.nvf.settings.vim.*`; both are normalized automatically. **Examples:** ```python # Search NixOS packages nix(action="search", query="firefox", source="nixos", type="packages") # Get package info nix(action="info", query="firefox", source="nixos", type="package") # Search Home Manager options nix(action="search", query="git", source="home-manager") # Browse darwin options nix(action="browse", source="darwin", query="system.defaults") # Search Nixvim options nix(action="search", query="telescope", source="nixvim") # Get Nixvim option info nix(action="info", query="plugins.telescope.enable", source="nixvim") # Search NVF options nix(action="search", query="vim.languages.nix", source="nvf") # Get NVF option info using a module wrapper path nix(action="info", query="programs.nvf.settings.vim.languages.nix.enable", source="nvf") # Browse NVF options below a prefix nix(action="browse", query="programs.nvf.vim.languages.nix", source="nvf") # Search FlakeHub nix(action="search", query="nixpkgs", source="flakehub") # Get FlakeHub flake info nix(action="info", query="NixOS/nixpkgs", source="flakehub") # Search Noogle for Nix functions nix(action="search", query="mapAttrs", source="noogle") # Get Noogle function info nix(action="info", query="lib.attrsets.mapAttrs", source="noogle") # Browse Noogle function categories nix(action="browse", source="noogle", query="lib.strings") # Search NixOS Wiki nix(action="search", query="nvidia", source="wiki") # Get Wiki page info nix(action="info", query="Flakes", source="wiki") # Search nix.dev documentation nix(action="search", query="packaging tutorial", source="nix-dev") # Search NixHub for package metadata nix(action="search", query="nodejs", source="nixhub") # Get detailed package info from NixHub (license, homepage, store paths) nix(action="info", query="python", source="nixhub") # Check binary cache status nix(action="cache", query="hello") # Check cache for specific version nix(action="cache", query="python", version="3.12.0") # Check cache for specific system nix(action="cache", query="firefox", system="x86_64-linux") # Get stats nix(action="stats", source="nixos", channel="stable") # List local flake inputs (requires Nix) nix(action="flake-inputs", type="list") # Browse files in a flake input nix(action="flake-inputs", type="ls", query="nixpkgs:pkgs/by-name") # Read a file from a flake input nix(action="flake-inputs", type="read", query="nixpkgs:flake.nix") # List or read a store path directly (requires Nix) nix(action="store", type="ls", query="/nix/store/<hash>-<name>") nix(action="store", type="read", query="/nix/store/<hash>-<name>/flake.nix") ``` ### `nix_versions` - Package Version History Find historical versions with nixpkgs commit hashes. Output includes: - Package metadata (license, homepage, programs) when available - Platform availability per version (Linux/macOS) - Nixpkgs commit hash for reproducible builds - Attribute path for Nix expressions ```python nix_versions(package, version, limit) ``` **Examples:** ```python # List recent versions with metadata nix_versions(package="python", limit=5) # Find specific version nix_versions(package="nodejs", version="20.0.0") ``` ## Installation **You DON'T need Nix installed.** This runs anywhere Python runs. ```bash # Run directly (no install) uvx mcp-nixos # Or install pip install mcp-nixos ``` For Nix users: ```bash nix run github:utensils/mcp-nixos nix profile install github:utensils/mcp-nixos ``` ### Declarative Installation (NixOS / Home Manager / nix-darwin) mcp-nixos is available in [nixpkgs](https://search.nixos.org/packages?channel=unstable&show=mcp-nixos&query=mcp-nixos): ```nix # NixOS (configuration.nix) environment.systemPackages = [ pkgs.mcp-nixos ]; # Home Manager (home.nix) home.packages = [ pkgs.mcp-nixos ]; # nix-darwin (darwin-configuration.nix) environment.systemPackages = [ pkgs.mcp-nixos ]; ``` Or use the flake directly with the provided overlay: ```nix # flake.nix { inputs = { nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable"; mcp-nixos.url = "github:utensils/mcp-nixos"; }; outputs = { self, nixpkgs, mcp-nixos, ... }: { # Example: NixOS configuration nixosConfigurations.myhost = nixpkgs.lib.nixosSystem { system = "x86_64-linux"; modules = [{ nixpkgs.overlays = [ mcp-nixos.overlays.default ]; environment.systemPackages = [ pkgs.mcp-nixos ]; }]; }; # Example: Home Manager standalone homeConfigurations.myuser = home-manager.lib.homeManagerConfiguration { pkgs = import nixpkgs { system = "x86_64-linux"; overlays = [ mcp-nixos.overlays.default ]; }; modules = [{ home.packages = [ pkgs.mcp-nixos ]; }]; }; }; } ``` `overlays.default` only adds `pkgs.mcp-nixos`. The package carries its own FastMCP 4 / MCP SDK 2 stack (see `nix/fastmcp4.nix`), including a starlette at or above the 1.0.1 security floor FastMCP requires, so nothing else in your Python package set changes, even on nixpkgs channels that still ship FastMCP 3. If you also want `pkgs.python3Packages.fastmcp` itself upgraded set-wide, apply `mcp-nixos.overlays.fastmcp4` in addition. ## Development ```bash nix develop # Enter dev shell nix build # Build package pytest tests/ # Run tests ruff check . # Lint ruff format . # Format mypy mcp_nixos/ # Type check ``` ## Acknowledgments - **[NixHub.io](https://www.nixhub.io)** - Package version history - **[search.nixos.org](https://search.nixos.org)** - Official NixOS search - **[FlakeHub](https://flakehub.com)** - Flake registry by Determinate Systems - **[Jetify](https://www.jetify.com)** - Creators of Devbox and NixHub - **[Noogle](https://noogle.dev)** - Nix function search engine - **[NuschtOS](https://github.com/NuschtOS/search)** - Static option search infrastructure powering Nixvim support - **[Nixvim](https://github.com/nix-community/nixvim)** - Neovim configuration framework for Nix - **[NVF](https://github.com/NotAShelf/nvf)** - Neovim configuration framework and published option catalogue ## License MIT - Because sharing is caring. --- *Created by James Brink. Maintained by mass̶o̶c̶h̶i̶s̶t̶s̶ enthusiasts who enjoy Nix.*