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The Excel (XLSX) skill for Claude

The XLSX skill is Anthropic's skill for spreadsheets. Claude uses it to create, read and fix .xlsx, .xlsm, .csv and .tsv files, and it insists on formulas over pasted numbers. Every workbook with formulas is recalculated through LibreOffice and checked for errors before the agent hands it back.

Source

When the agent reaches for it

The agent keeps every installed skill's description in view and loads the full instructions when a request matches. The license on this skill forbids copying its materials, so this page describes it rather than quoting it. Read the description at the source.

Why it recalculates every time

openpyxl writes a formula as text and stores no result. Open that file in pandas or most previewers and every formula cell reads as empty. The skill makes recalculation mandatory: a bundled script runs the workbook through LibreOffice, fills in the values, and reports any cell that evaluates to an error. The agent does not ship while that report has errors in it.

The rest of the skill is house rules that separate a spreadsheet you can use from one that only looks right. Totals are formulas, not numbers computed in Python. Hardcoded inputs are labelled with their source. An existing file's conventions win over every default.

  • Financial models follow banking conventions: blue inputs, black formulas, green cross-sheet links.
  • Percentages are stored as fractions and years as text, so neither renders wrong.
  • Messy CSVs with junk rows and misplaced headers are cleaned into proper tables.

What ships with it

Besides SKILL.md, the folder carries these. The agent opens them only when a step in the instructions calls for one.

  • scripts/ 51 files · 1.0 MB

Install the excel (XLSX) skill

In Claude Code, run this in a session. It comes from the publisher's own instructions.

Claude Code 
/plugin marketplace add anthropics/skills
/plugin install document-skills@anthropic-agent-skills

This skill is proprietary. Its license allows use through the publisher's own services and forbids copying its materials out of them, so install it the way the publisher provides rather than copying files.

Questions people ask

How do I install the excel (XLSX) skill?

In Claude Code, run /plugin marketplace add anthropics/skills, then /plugin install document-skills@anthropic-agent-skills. Its license is proprietary, so install it through the publisher's own route and do not copy the folder out of the repository.

When does the agent use the excel (XLSX) skill?

When a request matches its description. The agent keeps only the name and description of each installed skill in view, and reads the full instructions when a task fits. You can also ask for it by name.

Start with one machine.

Add the others when the work needs them, and the cloud when it has to keep going without you.

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