Chess FEN MCP Server

A Model Context Protocol (MCP) server that provides chess FEN notation validation and visualization capabilities.

Features

• Convert FEN (Forsyth-Edwards Notation) strings to ASCII chess board visualizations
• Easy integration with MCP-compatible AI assistants allowing them to validate their generated FEN strings
• Installable via npx

Installation

npx chess-fen-mcp

Or install globally:

npm install -g chess-fen-mcp

Usage

As MCP Server

Add to your MCP client configuration (Claude Desktop, etc.):

{
  "mcpServers": {
    "chess-fen": {
      "command": "npx",
      "args": ["chess-fen-mcp"]
    }
  }
}

If installed globally, you can also use:

{
  "mcpServers": {
    "chess-fen": {
      "command": "chess-fen-mcp"
    }
  }
}

Available Tools

visualize_fen

Converts a FEN string to an ASCII chess board visualization.

Parameters:

• fen_string (string, required): FEN notation string

Example Input:

fen_string: "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"

Example Output:

Fen {
  rows: 8,
  columns: 8,
  board: [
  a b c d e f g h
8 ♜ ♞ ♝ ♛ ♚ ♝ ♞ ♜ 8
7 ♟ ♟ ♟ ♟ ♟ ♟ ♟ ♟ 7
6 . . . . . . . . 6
5 . . . . . . . . 5
4 . . . . . . . . 4
3 . . . . . . . . 3
2 ♙ ♙ ♙ ♙ ♙ ♙ ♙ ♙ 2
1 ♖ ♘ ♗ ♕ ♔ ♗ ♘ ♖ 1
  a b c d e f g h
  ],
  toMove: 'white',
  castlingRights: {
    white: { queenside: true, kingside: true },
    black: { queenside: true, kingside: true }
  },
  enPassantSquare: '-',
  halfMoves: 0,
  fullMoves: 1
}

Development

git clone
cd chess-fen-mcp
npm install
npm run dev

License

MIT