Agent skill · software engineering · anthropics
xlsx-author
Produce a .xlsx file on disk (headless) instead of driving a live Excel workbook — for managed-agent sessions with no open Office app.
Why this skill is useful
Provides a Python script using openpyxl to generate .xlsx files in a headless environment, which is not commonly known.
What it needs
Requires openpyxl, python installed locally. About 1k tokens when loaded. Last updated 2026-08-04. 34,059 stars on the source repository.
What this skill does
xlsx-author Use this skill when running headless (managed-agent / CMA mode) and you need to deliver an Excel workbook as a file artifact rather than editing a live workbook via mcpofficeexcel. Output contract Write to ./out/<name>.xlsx. Create ./out/ if it does not exist. Return the relative path in your final message so the orchestration layer can collect it. How to build the workbook Write a short Python script and run it with Bash. Use openpyxl: Conventions (mirror audit-xls) Blue / black / green. Blue = hardcoded input, black = formula, green = link to another sheet/file. No hardcodes in calc cells. Every calculation cell is a formula; every input lives on an Inputs tab. Named ranges for any value referenced from a deck or memo. Balance checks. Include a Checks tab that ties (BS balances, CF ties to cash, etc.) and surfaces TRUE/FALSE. One model per file. Do not append to an existing workbook unless explicitly asked. When NOT to use If mcpofficeexcel tools are available (Cowork plugin mode), use those instead — they drive the user's live workbook with review checkpoints. This skill is the file-producing fallback for headless runs.
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills anthropics/xlsx-author--f14345