MCP-MongoDB-MySQL-Server

Instructions

Implementation Reference

• src/index.ts:722-753 (handler)

  The handler function that executes INSERT, UPDATE, or DELETE SQL queries on a MySQL database connection. Ensures connection, validates non-SELECT query, executes with optional parameters, and returns JSON result.

  private async handleExecute(args: any) {
    await this.ensureConnection();
  
    if (!args.sql) {
      throw new McpError(ErrorCode.InvalidParams, 'SQL query is required');
    }
  
    const sql = args.sql.trim().toUpperCase();
    if (sql.startsWith('SELECT')) {
      throw new McpError(
        ErrorCode.InvalidParams,
        'Use query tool for SELECT statements'
      );
    }
  
    try {
      const [result] = await this.connection!.query(args.sql, args.params || []);
      return {
        content: [
          {
            type: 'text',
            text: JSON.stringify(result, null, 2),
          },
        ],
      };
    } catch (error) {
      throw new McpError(
        ErrorCode.InternalError,
        `Query execution failed: ${getErrorMessage(error)}`
      );
    }
  }

• src/index.ts:280-300 (schema)

  The input schema for the 'execute' tool, defining required 'sql' string for non-SELECT queries and optional 'params' array.

  {
    name: 'execute',
    description: 'Execute an INSERT, UPDATE, or DELETE query',
    inputSchema: {
      type: 'object',
      properties: {
        sql: {
          type: 'string',
          description: 'SQL query (INSERT, UPDATE, DELETE)',
        },
        params: {
          type: 'array',
          items: {
            type: ['string', 'number', 'boolean', 'null'],
          },
          description: 'Query parameters (optional)',
        },
      },
      required: ['sql'],
    },
  },

• src/index.ts:541-542 (registration)

  Registration in the CallToolRequestHandler switch statement that routes 'execute' tool calls to the handleExecute method.

  case 'execute':
    return await this.handleExecute(request.params.arguments);