xlsx Skill (Anthropic) for Claude: Create, Edit and Fix Spreadsheets

Makes Claude create, edit and clean spreadsheet files (.xlsx, .xlsm, .csv, .tsv) with working formulas and a recalculation check.

Installs: 191.6K; on skills.sh
Stars: 186.4K; on GitHub
Files: 52; besides SKILL.md
Updated: Oct 2026; last repo commit

xlsx tells Claude how to handle spreadsheet files: read, edit, create and convert .xlsx, .xlsm, .xltx, .csv and .tsv. It triggers whenever a spreadsheet file is the main input or output, even when you only say "the xlsx in my downloads". It does not trigger when the result should be a Word document, an HTML report, a standalone script or a Google Sheets integration.

Claude builds files with openpyxl and pandas. It writes formulas, not pasted totals, then runs the bundled recalc.py, which uses LibreOffice to compute every formula and report errors. The skill bundles 52 files, mostly XML schemas, and its license is proprietary, so read LICENSE.txt before you reuse its files.

Good for

Analysts and finance people who want Claude to build or fix a workbook file
Anyone with a messy CSV or sheet that needs cleaning into a proper spreadsheet
Developers who want spreadsheet output with live formulas, not pasted numbers

Install xlsx

Claude Code

Copy this prompt.

Install the xlsx skill in Claude Code. Run this command:

npx skills add https://github.com/anthropics/skills --skill xlsx

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js.

From its listing on skills.sh. Source.

What's in the skill

When it loads

Use this skill any time a spreadsheet file is the primary input or output. This means any task where the user wants to: open, read, edit, or fix an existing .xlsx, .xlsm, .xltx, .csv, or .tsv file (e.g., adding columns, computing formulas, formatting, charting, cleaning messy data); create a new spreadsheet from scratch or from other data sources; or convert between tabular file formats. Trigger especially when the user references a spreadsheet file by name or path — even casually (like "the xlsx in my downloads") — and wants something done to it or produced from it. Also trigger for cleaning or restructuring messy tabular data files (malformed rows, misplaced headers, junk data) into proper spreadsheets. The deliverable must be a spreadsheet file. Do NOT trigger when the primary deliverable is a Word document, HTML report, standalone Python script, database pipeline, or Google Sheets API integration, even if tabular data is involved.

Sections in SKILL.md

Requirements for every output
Recalculate (mandatory whenever the file contains formulas)
Choosing formulas that survive verification
openpyxl gotchas
Financial models
Dependencies

Key facts

Author: Anthropic (anthropics/skills)
License: Proprietary (LICENSE.txt has the terms)
Installs on skills.sh: 191,618 (Nov 2, 2026)
GitHub stars: 186,362 (Nov 2, 2026)
skills.sh audits: Gen Agent Trust Hub: pass, Socket: warn, Snyk: pass
Last commit: 2026-10-28
Files: 52 bundled files: LICENSE.txt, scripts/recalc.py, scripts/office/ (soffice.py, validate.py, validators, helpers and 39 .xsd schemas)
Needs: openpyxl, pandas, markitdown and LibreOffice (soffice)
Triggers on: Any task where a spreadsheet file is the main input or output

What it includes

Builds or changes workbooks with formulas and formatting
For files with formulas and formatting Claude uses openpyxl. Formulas are written as formulas (such as =SUM(B2:B9)), never as pasted results.
Runs code · Create and edit with openpyxl
Reads and writes large tables through read_excel and to_excel
For big data in or out of a sheet Claude uses pandas.
Runs code · Bulk data with pandas
Dumps each sheet as text so Claude can see what is in the file
markitdown prints one section per sheet. It gives no cell coordinates, so Claude does not plan edits from it.
Runs code · Quick look with markitdown
Recalculates every formula in LibreOffice and reports errors as JSON
The file is rewritten in place and the script reports total formulas and total errors. Claude fixes the cells it names and runs it again until there are no errors.
Runs code · scripts/recalc.py
Avoids functions LibreOffice cannot evaluate, such as XLOOKUP and FILTER
The skill steers Claude to SUMIFS, INDEX and MATCH, and to the _xlfn. prefix for six newer functions. It avoids XLOOKUP, XMATCH, SORT, FILTER, UNIQUE and SEQUENCE.
Read · Formula rules
Blue inputs, black formulas, green sheet links, one cell per assumption
Unless you say otherwise, the skill sets colors for inputs and formulas, number formats, and a labeled cell for each assumption.
Write · Financial model conventions

From the official docs

Permissions

Medium risk

The skill runs Python scripts and LibreOffice, and it overwrites the spreadsheet it recalculates. Work on a copy of any workbook you cannot lose, and approve the commands Claude asks to run.

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It rewrites your spreadsheet in place
recalc.py recalculates through LibreOffice and saves over the file. Keep a copy of important workbooks before Claude runs it.
It runs Python and LibreOffice on your machine
The skill tells Claude to run scripts and the soffice command, and to install a missing package with pip. Approve each command in Claude Code and check what it installs.
Saving a data-only workbook deletes formulas
The SKILL.md warns that opening with data_only=True and saving replaces every formula with its value. Ask Claude to confirm it never saves such a file over your original.

Questions

What does the xlsx skill do?

It makes Claude create, edit, clean and convert spreadsheet files. It keeps formulas live and runs a recalculation script so the file has no formula errors before Claude hands it back.

How do I install it in Claude Code?

Use the install box above, which adds it from the anthropics/skills repo. Claude then uses it when you mention a spreadsheet file, for example "clean up sales.csv and save it as an xlsx with totals".

What does it need on my machine?

The SKILL.md lists openpyxl, pandas, markitdown and LibreOffice. It says the Python packages are preinstalled in its environment, so on your own machine you may need to install them.

Why does Claude avoid XLOOKUP?

The skill says the LibreOffice used for recalculation cannot evaluate XLOOKUP, FILTER, SORT and similar functions. They would turn into #NAME? errors in the delivered file, so Claude uses INDEX and MATCH instead.

Does it work for Word or Google Sheets?

No. The SKILL.md says not to trigger when the main result is a Word document, an HTML report, a standalone script, a database pipeline or a Google Sheets API integration.

Can I reuse its files?

The SKILL.md lists the license as proprietary and points to LICENSE.txt for the terms. Read that file before you copy or redistribute anything.

Is it safe to install?

It runs Python scripts and LibreOffice on your files, and recalc.py rewrites the spreadsheet in place. Work on a copy of important files and read the permissions section on this page.

Information

updated Nov 2, 2026

Repository: anthropics/skills
Folder: skills/xlsx

anthropics/skills skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 3

SKILL.md · github.com
skills.sh listing · skills.sh
GitHub repo · github.com