The problem
How it works
Anthropic's skills repository ships an xlsx skill among its document skills, shared as a reference for the skills behind Claude's own file creation. It tells the agent to edit workbooks with openpyxl, read bulk data with pandas, keep calculations as live Excel formulas rather than pasted numbers, and run a bundled recalculation script through LibreOffice that reports formula counts and errors. In Claude Code the skills install through the plugin marketplace.
Results and limitations
The repository documents the skill rather than reporting results. Anthropic labels the skills as demonstrations whose behaviour may differ from Claude in practice, and the skill itself warns that a clean recalculation only shows formulas evaluate, not that they are right.
Before you try it
The skill steers away from newer functions such as XLOOKUP and FILTER because LibreOffice may not evaluate them reliably, and warns that re-saving workbooks with external links through openpyxl can break them. Work on a copy, spot-check a few formulas by hand, and keep confidential financial files out of any session you are not allowed to use for them. The README describes the document skills as open source, and the folder has its own LICENSE.txt; read it before reusing the files. Results depend on your setup and were not independently reproduced by Top 200 Repos.
Tools and repositories
- Tools
- Claude Code · anthropics/skills document-skills plugin · Python with openpyxl and pandas · LibreOffice
- Prerequisites
- Claude Code with the document skills installed, Python libraries available, and LibreOffice for recalculation.
Try it yourself: Build a checked spreadsheet model
Fill the fields to adapt the prompt. Empty fields stay as visible [placeholders].
Using the xlsx skill, build [New workbook name].xlsx from the data in [Source data file]. Create a sheet called Inputs that holds every assumption with a label and a source note, and a sheet called [Calculation sheet name] that calculates [What to calculate] with live Excel formulas referencing Inputs, not numbers computed in Python. Use widely supported functions only. After saving, run the recalculation check and fix every formula error, then show me five formulas with their cell address and the value each should return, so I can spot-check them. Do not overwrite [Source data file]; save the new workbook next to it.Check a handful of formulas yourself; an error-free recalculation does not prove the logic is correct.
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Sources
- anthropics/skills README (opens in a new tab)
Project documentation · github.com · Undated · Source checked 11 Nov 2026, 22:04 UTC
What this source supports
- Skills are folders of instructions and scripts that Claude loads when relevant
- Claude Code adds them with /plugin marketplace add anthropics/skills and a document-skills plugin
- The docx, pdf, pptx and xlsx document skills are shared as references
- Skills are for demonstration and should be tested before critical use
- xlsx skill (SKILL.md) (opens in a new tab)
Project documentation · github.com · Undated · Source checked 11 Nov 2026, 22:04 UTC
What this source supports
- Uses openpyxl for formulas and formatting, pandas for bulk data and LibreOffice for recalculation
- Requires live formulas instead of values computed in Python
- A recalculation script reports formula counts and errors
- Advises avoiding XLOOKUP, FILTER and other newer functions LibreOffice may not evaluate
- Suggests colour conventions for financial models, such as blue for hardcoded inputs