Excel Finance MCP

# Excel MCP Formula Implementation Summary ## ✅ Completed Implementation ### Core Requirements Met 1. **Formula Preservation**: All calculations now use Excel formulas instead of hardcoded values 2. **Transparency**: Users can see exactly how values are calculated by clicking on cells 3. **Auto-calculation**: Formulas are automatically calculated when Excel files are opened 4. **Professional Standards**: Spreadsheets look and behave as if created manually by a professional ## 🔧 Technical Changes ### 1. Enhanced Excel Manager (`src/excel/excel-manager.ts`) - Added `writeCellWithFormula()` method for writing formulas directly - Added `createFormulaCell()` static method for creating formula-based cells - Added `validateCellHasFormula()` to verify cells contain formulas - Added `ensureFormulasInWorksheet()` to configure auto-calculation - Updated `writeWorksheet()` to properly handle formula cells - Updated `saveWorkbook()` to ensure formulas calculate on file open ### 2. New Excel Tools (`src/tools/excel-tools.ts`) Added three new tools for formula management: #### `excel_write_calculation` - Writes calculations using formulas (SUM, AVERAGE, etc.) - Supports custom formulas - Ensures transparency in all calculations #### `excel_validate_formulas` - Validates that specified cells contain formulas - Reports any cells with hardcoded values - Essential for audit compliance #### `excel_ensure_formula_calculation` - Configures worksheets for automatic formula calculation - Ensures formulas update when source data changes ## 📝 How It Works ### Creating a Calculation Instead of writing a hardcoded value: ```javascript // ❌ WRONG cell.value = 4; ``` The system now writes a formula: ```javascript // ✅ CORRECT cell.value = { formula: '=A1+A2' }; ``` ### In Excel - **Cell Display**: Shows the calculated result (e.g., "4") - **Formula Bar**: Shows the formula when cell is selected (e.g., "=A1+A2") - **Auto-update**: Values recalculate when source cells change ## 🎯 Example Usage ```javascript // Create a worksheet with formulas await manager.createWorkbook([{ name: 'Sheet1', data: [ ['Value 1', 'Value 2', 'Total'], [10, 20, { formula: '=A2+B2', value: null }], // Shows 30 [15, 25, { formula: '=A3+B3', value: null }], // Shows 40 ['', 'Sum:', { formula: '=SUM(C2:C3)', value: null }] // Shows 70 ] }]); ``` ## 📊 Benefits 1. **Auditability**: Every calculation can be traced and verified 2. **Transparency**: No "black box" calculations 3. **Professionalism**: Meets accounting and financial standards 4. **Maintainability**: Formulas update automatically when data changes 5. **Compliance**: Aligns with GAAP, IFRS, and SOX requirements ## 🔍 Testing Created `test-formula.js` that demonstrates: - Creating cells with formulas - Automatic calculation on file open - Proper formula display in Excel Test file `formula-example.xlsx` includes: - Product calculations (Quantity × Price) - Subtotal using SUM formula - Tax calculation (10% of subtotal) - Grand total calculation ## 📚 Documentation - `FORMULA_RULES.md`: Comprehensive guide on formula requirements - `test-formula.js`: Working example of formula implementation - `IMPLEMENTATION_SUMMARY.md`: This document ## ✨ Key Takeaway **Every calculated value in the Excel MCP server now uses transparent, auditable formulas - exactly as a professional would create them manually in Excel.**