xlsx

Official

Built for serious spreadsheet work where you need actual Excel files as output, not just data analysis.

anthropics ↓ 139k

Claude Code

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What it does

Professional font (Arial, Times New Roman) throughout, unless the user says otherwise.
Use formulas, never hardcoded results. Write sheet['B10'] = '=SUM(B2:B9)', not the Python-computed total. The sheet must recalculate when its inputs change.
Prefer Excel-2007-era functions — SUMIFS, INDEX, MATCH, IFERROR, SUMPRODUCT — which need no prefix.
A formula LibreOffice could not parse is written back lowercased — a quick tell beside a #NAME?.
dataonly=True is destructive if you save. That workbook has no formulas left, so saving replaces every one with a literal — permanently.
dataonly=True on a file openpyxl just wrote returns None everywhere — run recalc.py first. (A formula whose result is "" also reads back as None.)
Merged cells: write the top-left anchor only. Every other cell in the range is a MergedCell whose .value is read-only.

Requirements & configuration

Prefer Excel-2007-era functions — SUMIFS, INDEX, MATCH, IFERROR, SUMPRODUCT — which need no prefix.

Configuration: SUMIFSINDEXMATCHIFERRORSUMPRODUCTXLOOKUPXMATCHSORT

Derived from the skill's own SKILL.md documentation · extracted 2026-07-23

Built for serious spreadsheet work where you need actual Excel files as output, not just data analysis.

Source

Repository: https://github.com/anthropics/skills

xlsx FAQ

What does the xlsx skill do?

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. Professional font (Arial, Times New Roman) throughout, unless the user says otherwise. Use formulas, never hardcoded results. Write sheet['B10'] = '=SUM(B2:B9)', not the Python-computed total. The sheet must recalculate when its inputs change.

What does xlsx require?

Prefer Excel-2007-era functions — SUMIFS, INDEX, MATCH, IFERROR, SUMPRODUCT — which need no prefix. Configuration keys: SUMIFS, INDEX, MATCH, IFERROR, SUMPRODUCT, XLOOKUP, XMATCH, SORT.

How do I install xlsx?

Run: npx -y skills add https://github.com/anthropics/skills --skill xlsx --agent claude-code — the source lives at github.com/anthropics/skills.

Maintain xlsx?

Let people know it's listed here — add the badge (live metrics, light/dark aware) or a plain link to your README or docs.

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npx agentictools info skills/anthropics-skills-xlsx

The second line is the CLI lookup for this page — handy in READMEs and docs.