MySQL Server MCP Server

src
mysql-server
src/mysql-server/index.ts
#!/usr/bin/env node
import { Server } from '@modelcontextprotocol/sdk/server/index.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
import {
  CallToolRequestSchema,
  ErrorCode,
  ListToolsRequestSchema,
  McpError,
} from '@modelcontextprotocol/sdk/types.js';
import mysql from 'mysql2/promise';

const DB_CONFIG = {
  host: process.env.MYSQL_HOST,
  user: process.env.MYSQL_USER,
  password: process.env.MYSQL_PASSWORD,
  database: process.env.MYSQL_DATABASE,
};

class MySQLServer {
  private server: Server;
  private pool: mysql.Pool;

  constructor() {
    this.server = new Server(
      {
        name: 'mysql-server',
        version: '0.1.0',
      },
      {
        capabilities: {
          tools: {},
        },
      }
    );

    this.pool = mysql.createPool(DB_CONFIG);

    this.setupToolHandlers();
    
    this.server.onerror = (error) => console.error('[MCP Error]', error);
    process.on('SIGINT', async () => {
      await this.server.close();
      process.exit(0);
    });
  }

  private setupToolHandlers() {
    this.server.setRequestHandler(ListToolsRequestSchema, async () => ({
      tools: [
        {
          name: 'query',
          description: 'Execute SQL query',
          inputSchema: {
            type: 'object',
            properties: {
              sql: {
                type: 'string',
                description: 'SQL query to execute',
              },
            },
            required: ['sql'],
          },
        },
      ],
    }));

    this.server.setRequestHandler(CallToolRequestSchema, async (request) => {
      if (request.params.name !== 'query') {
        throw new McpError(
          ErrorCode.MethodNotFound,
          `Unknown tool: ${request.params.name}`
        );
      }

      const args = request.params.arguments as { sql: string };
      const { sql } = args;
      if (typeof sql !== 'string') {
        throw new McpError(
          ErrorCode.InvalidParams,
          'SQL query must be a string'
        );
      }

      try {
        const connection = await this.pool.getConnection();
        const [rows] = await connection.query(sql);
        connection.release();

        return {
          content: [
            {
              type: 'text',
              text: JSON.stringify(rows, null, 2),
            },
          ],
        };
      } catch (error) {
        if (error instanceof Error) {
          return {
            content: [
              {
                type: 'text',
                text: `MySQL error: ${error.message}`,
              },
            ],
            isError: true,
          };
        }
        throw error;
      }
    });
  }

  async run() {
    const transport = new StdioServerTransport();
    await this.server.connect(transport);
    console.error('MySQL MCP server running on stdio');
  }
}

const server = new MySQLServer();
server.run().catch(console.error);