MCP Server MySQL

Instructions

Implementation Reference

• src/index.ts:100-139 (handler)

  The handler function for the 'connect' tool. It creates a MySQL connection pool using the provided parameters or falls back to environment variables, closes any existing pool, tests the new connection by acquiring and releasing it, and returns a success message with connection details.

  async ({ host, port, user, password, database }) => {
    const config = {
      host: host || process.env.MYSQL_HOST || "localhost",
      port: port || parseInt(process.env.MYSQL_PORT || "3306", 10),
      user: user || process.env.MYSQL_USER || "root",
      password: password || process.env.MYSQL_PASSWORD || "",
      database: database,
      waitForConnections: true,
      connectionLimit: 10,
      queueLimit: 0,
    };
  
    // Close existing pool if any
    if (pool) {
      await pool.end();
    }
  
    pool = mysql.createPool(config);
  
    // Test connection
    const connection = await pool.getConnection();
    connection.release();
  
    const output = {
      success: true,
      host: config.host,
      port: config.port,
      database: config.database || null,
    };
  
    return {
      content: [
        {
          type: "text" as const,
          text: `Successfully connected to MySQL server at ${config.host}:${config.port}${config.database ? ` (database: ${config.database})` : ""}`,
        },
      ],
      structuredContent: output,
    };
  }

• src/index.ts:93-99 (schema)

  Zod schema defining the optional input parameters for the 'connect' tool: host, port, user, password, and database.

  {
    host: z.string().optional().describe("Database host"),
    port: z.number().optional().describe("Database port"),
    user: z.string().optional().describe("Database user"),
    password: z.string().optional().describe("Database password"),
    database: z.string().optional().describe("Database name"),
  },

• src/index.ts:89-140 (registration)

  Registration of the 'connect' tool on the MCP server using server.tool(), specifying the tool name, description, input schema, and handler function.

  // Tool: connect
  server.tool(
    "connect",
    "Connect to a MySQL database. If not called explicitly, will use environment variables for connection.",
    {
      host: z.string().optional().describe("Database host"),
      port: z.number().optional().describe("Database port"),
      user: z.string().optional().describe("Database user"),
      password: z.string().optional().describe("Database password"),
      database: z.string().optional().describe("Database name"),
    },
    async ({ host, port, user, password, database }) => {
      const config = {
        host: host || process.env.MYSQL_HOST || "localhost",
        port: port || parseInt(process.env.MYSQL_PORT || "3306", 10),
        user: user || process.env.MYSQL_USER || "root",
        password: password || process.env.MYSQL_PASSWORD || "",
        database: database,
        waitForConnections: true,
        connectionLimit: 10,
        queueLimit: 0,
      };
  
      // Close existing pool if any
      if (pool) {
        await pool.end();
      }
  
      pool = mysql.createPool(config);
  
      // Test connection
      const connection = await pool.getConnection();
      connection.release();
  
      const output = {
        success: true,
        host: config.host,
        port: config.port,
        database: config.database || null,
      };
  
      return {
        content: [
          {
            type: "text" as const,
            text: `Successfully connected to MySQL server at ${config.host}:${config.port}${config.database ? ` (database: ${config.database})` : ""}`,
          },
        ],
        structuredContent: output,
      };
    }
  );