# SPDX-License-Identifier: GPL-3.0-or-later
"""MCP server for Nixpkgs, NixOS and Home Manager."""
import argparse
import os
from fastmcp import FastMCP
mcp = FastMCP("mcp-nix")
# All available tools (flat list, all enabled by default)
ALL_TOOLS = [
# Nixpkgs
"search_nixpkgs",
"read_derivation",
# Options (unified)
"search_options",
"list_versions",
"show_option_details",
"read_option_declaration",
# NixHub
"find_nixpkgs_commit_with_package_version",
# Noogle
"search_nix_stdlib",
"help_for_stdlib_function",
]
def parse_args() -> argparse.Namespace:
"""Parse CLI arguments."""
parser = argparse.ArgumentParser(
description="MCP server for Nixpkgs, NixOS and Home Manager",
)
parser.add_argument(
"--exclude",
type=str,
default="",
help=f"Comma-separated list of tool names to exclude. Available: {', '.join(ALL_TOOLS)}",
)
# Deprecated flags - kept for backwards compatibility, silently ignored
parser.add_argument("--nixpkgs", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--options", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--nixhub", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--noogle", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--nixos", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--homemanager", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--nixvim", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--nix-darwin", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--impermanence", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--microvm", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--nix-nomad", action=argparse.BooleanOptionalAction, default=None, help=argparse.SUPPRESS)
parser.add_argument("--include", type=str, default="", help=argparse.SUPPRESS)
return parser.parse_args()
def parse_tool_list(value: str) -> set[str]:
"""Parse a comma-separated list of tool names."""
if not value:
return set()
return {name.strip() for name in value.split(",") if name.strip()}
def validate_tool_names(names: set[str], arg_name: str) -> None:
"""Validate that all names are valid tools."""
valid_names = set(ALL_TOOLS)
for name in names:
if name not in valid_names:
print(f"Error: Unknown tool '{name}' in {arg_name}. Available: {', '.join(sorted(valid_names))}")
raise SystemExit(1)
def main() -> None:
"""Run the MCP server."""
args = parse_args()
# Parse and validate exclude list
exclude = parse_tool_list(args.exclude)
validate_tool_names(exclude, "--exclude")
# All tools enabled by default, minus excluded ones
included_tools = set(ALL_TOOLS) - exclude
from . import tools as _tools # noqa: F401
for tool in ALL_TOOLS:
if tool not in included_tools:
mcp.remove_tool(tool)
try:
mcp.run()
except KeyboardInterrupt:
os._exit(0)
if __name__ == "__main__":
main()
