nixos-wiki-mcp

An MCP server that reads wiki entries from an offline dump of the official NixOS Wiki.

Download a wiki dump here (updated daily). The wikidump.xml.zst file is a compressed MediaWiki XML export. A small indexer compresses it once into a local SQLite database for fast lookups, and the MCP server exposes three tools over stdio:

Tool	Description
list_pages	List the titles of all pages in the index.
search_pages	Search page titles by substring (case-insensitive).
get_page	Get a page's full wikitext and metadata by exact title.

Setup

Build the index

First, build the SQLite index from the wiki dump:

nix develop -c cargo run --release --bin wikimbp-index

This reads ./wikidump.xml.zst and writes ./wiki-index.sqlite3.

You should see output like:

indexed 7498 pages into wiki-index.sqlite3 in 4.6s

Build & run the server

Build the MCP server:

nix build

This produces ./result/bin/wikimbp-server (and ./result/bin/wikimbp-index).

The server reads its database from the NIXOS_WIKI_DB environment variable (defaults to wiki-index.sqlite3 in the current directory). Run it so your MCP client can spawn it as a stdio subprocess:

NIXOS_WIKI_DB=$PWD/wiki-index.sqlite3 nix run

Configure your MCP client

Point your MCP client at nix to run the server via flakes. The server speaks the standard MCP protocol over stdio. There is no HTTP endpoint and no registration server.

Example entry:

{
  "mcpServers": {
    "nixos-wiki": {
      "command": "nix",
      "args": ["run", "path:/absolute/path/to/project"],
      "env": {
        "NIXOS_WIKI_DB": "/absolute/path/to/wiki-index.sqlite3"
      }
    }
  }
}

Smoke-test the server

You can drive the server manually by piping JSON-RPC requests to it over stdin:

printf '%s\n' \
  '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{}}' \
  '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"get_page","arguments":{"title":"Btrfs"}}}' \
  | NIXOS_WIKI_DB=$PWD/wiki-index.sqlite3 nix run

Development

nix develop
cargo build                       # build both binaries
cargo test                        # run the test suite
cargo run --bin wikimbp-index     # rebuild the index
cargo run --bin wikimbp-server    # run the MCP server