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Claude skill · Documents · Anthropic

Excel spreadsheets (XLSX) skill for Claude

Anthropic’s skill for spreadsheets: reading and cleaning data, writing formulas that recalculate correctly, and building financial models.

Command
/xlsx
Licence
Proprietary: no copies, link only
Folder
53 files, 1.1 MB
Runs code
12 scripts

Overview

What it does

The XLSX skill is about producing spreadsheets that still work when someone opens them. It uses openpyxl and pandas, and insists on real formulas rather than totals computed in Python, so the sheet recalculates when its inputs change. After writing, LibreOffice recalculates the workbook so formula errors show up before the file is handed over.

One section explains which formulas survive that check and which don’t, since LibreOffice supports fewer functions than Excel. There is also a section of conventions for financial models, such as colour-coding inputs and documenting assumptions.

Triggers

When Claude uses it

  • A spreadsheet is the main input or output: .xlsx, .xlsm, .xltx, .csv or .tsv.
  • Adding columns, formulas, formatting or charts; cleaning messy tabular data.
  • Not when the deliverable is a Word document, HTML report or database pipeline.

What it needs

  • Python with openpyxl, pandas and markitdown; LibreOffice for recalculation.
  • Proprietary licence: use it through Claude or the official plugin only.

Install

How to install it

Claude Code

Plugin (type in Claude Code)
/plugin marketplace add anthropics/skills
/plugin install document-skills@anthropic-agent-skills

The document-skills plugin installs 4 skills from this repository, including this one. Its skills are then namespaced, such as /document-skills:xlsx.

Its licence doesn’t allow copies, so we don’t give a copy command. Install it with the plugin above.

claude.ai and the Claude API

Anthropic runs this skill for you. It’s built into claude.ai when code execution is on, and on the API you reference it as xlsx:

Messages API request (excerpt)
{
  "container": {
    "skills": [
      {
        "type": "anthropic",
        "skill_id": "xlsx",
        "version": "latest"
      }
    ]
  },
  "tools": [
    {
      "type": "code_execution_20250825",
      "name": "code_execution"
    }
  ]
}

Checks

SKILL.md validator results

Its SKILL.md (99 lines) run through our SKILL.md validator, with the folder’s file list, for both targets. These check the file’s format, not whether the skill works well.

Claude Code

0 errors, 1 warning, 1 tip

  • warningClaude Code reads $0, $1 and so on as argument placeholders, so text like $B$2 (a price or a spreadsheet reference) can be replaced when the skill runs. Put a backslash before the $, such as \$5.00, to keep it as written.
  • tipSKILL.md doesn’t mention scripts/office/helpers/pptx_chart.py, scripts/office/helpers/pptx_slide.py, scripts/office/helpers/pptx_theme.py, scripts/office/helpers/__init__.py, scripts/office/schemas/ecma/fouth-edition/opc-contentTypes.xsd and 44 more. Say what each file is for and when to read or run it, or Claude won’t know to use it.

claude.ai and the API

0 errors, 0 warnings, 2 tips

  • tipThe Claude Help Center’s upload guide gives a 200-character description limit for claude.ai, though the platform docs say 1,024. Keep it under 200 if you’ll upload it there.
  • tipSKILL.md doesn’t mention scripts/office/helpers/pptx_chart.py, scripts/office/helpers/pptx_slide.py, scripts/office/helpers/pptx_theme.py, scripts/office/helpers/__init__.py, scripts/office/schemas/ecma/fouth-edition/opc-contentTypes.xsd and 44 more. Say what each file is for and when to read or run it, or Claude won’t know to use it.

Folder

What’s in the folder

  • LICENSE.txt1.4 KB
  • SKILL.md8.4 KB
  • scripts/51 files, 1.0 MB

Source

Licence and source

Related

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