XLSX
Officialby Anthropic
The XLSX Agent Skill from Anthropic gives Claude the ability to read, create, edit, and analyze Excel spreadsheets with professional-grade formatting and formula support. It triggers automatically whenever a spreadsheet file is the primary input or output of a conversation — whether you're opening an existing .xlsx file, creating a new financial model from scratch, converting between tabular formats, or cleaning messy data into structured spreadsheets. Under the hood, the skill uses pandas for data analysis and bulk operations, openpyxl for complex Excel formatting and formula construction, and LibreOffice for mandatory formula recalculation. This combination ensures that every spreadsheet Claude produces contains live, dynamic formulas rather than hardcoded values — a critical distinction for financial models and data analysis workflows. The skill enforces industry-standard conventions including financial model color coding (blue for inputs, black for formulas, green for internal links, red for external links), proper number formatting with unit notation, and comprehensive error detection that scans all cells for Excel errors like #REF!, #DIV/0!, and #NAME?. When editing existing files, it preserves the original formatting and style conventions exactly, making it safe to use on templates and existing workbooks. Built by Anthropic and available through the official skills repository, the XLSX skill works across Claude.ai, Claude Code, and the API without modification.
Installation
Key Features
- ✓Read, create, and edit .xlsx, .xlsm, .csv, and .tsv files with full formula support
- ✓Mandatory formula recalculation via LibreOffice ensures spreadsheets contain live dynamic formulas, not hardcoded values
- ✓Professional formatting with font control, cell fills, alignment, column widths, and multi-sheet workbook support
- ✓Financial model standards: industry-standard color coding, currency notation ($mm), percentages, and parenthetical negatives
- ✓Comprehensive error detection scans all cells for #REF!, #DIV/0!, #VALUE!, #N/A, and #NAME? errors
- ✓Data cleaning capabilities restructure messy tabular data with malformed rows and misplaced headers
Use Cases
- →Build financial models with revenue projections, valuation tables, and proper formula conventions from natural language descriptions
- →Analyze large datasets by reading existing spreadsheets, computing statistics, and adding visualization-ready summary sheets
- →Clean and restructure messy CSV exports into professional formatted Excel workbooks with proper headers and data types
- →Convert between file formats — transform CSV, TSV, or raw data into properly formatted .xlsx files with formulas and styling
- →Update existing Excel templates by modifying cells, inserting rows, and adding formulas while preserving the original formatting