Agent skill

XLSX Skill

by OpenLoaf in OpenLoaf/OpenLoaf

Unified read / write / stats / recalc / chart capability for Excel / CSV (.xlsx / .xlsm / .csv / .tsv).

AGPL-3.0Auto-check passedDocuments & Office

Install XLSX Skill

skills CLI
$ npx skills add OpenLoaf/OpenLoaf --skill xlsx-skill -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install OpenLoaf/OpenLoaf xlsx-skill --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/OpenLoaf/OpenLoaf.git skills-src && mkdir -p .claude/skills && cp -r skills-src/apps/server/src/ai/builtin-skills/xlsx/en .claude/skills/xlsx-skill && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
xlsx-skill
GitHub stars
108
Token cost
~1.9k tokens
SKILL.md length
326 words
Files
1
Skills in repo
33
Repo updated
First seen
Licence
AGPL-3.0

At a glance

Unified read / write / stats / recalc / chart capability for Excel / CSV (.xlsx / .xlsm / .csv / .tsv).

  • Works in 4 steps: Read: Start with ExcelInspect(summary) → Write: JsSandbox + exceljs → Format Conversion → …
  • Scenarios: reading cells
  • SKILL.md covers Tool List, 1. Read: Start with…, 2. Write: JsSandbox + exceljs and 3. Format Conversion, plus 1 more section
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

XLSX Skill is an agent skill from OpenLoaf/OpenLoaf. Unified read / write / stats / recalc / chart capability for Excel / CSV (.xlsx / .xlsm / .csv / .tsv). Trigger scenarios: reading cells, summarizing, grouping, highest/lowest values, total revenue, editing cell values or formulas, inserting rows/columns, adding total rows, inserting charts (bar/line/pie), freezing panes, auto-filter, conditional formatting, CSV ↔ XLSX conversion, building rosters / sales sheets / financial models, diagnosing REF! / DIV/0! formula errors, triggering recalculation. Typical…

Its SKILL.md is about 1.9k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Documents & Office, covering Excel spreadsheets and CSV and tabular files. It works with Microsoft Excel. The repository describes itself as: 🍞Open-source, local-first AI workspace with Agents, multi-model chat (GPT/Claude/Gemini/DeepSeek), Notion-like docs, AI image & video generation, email, calendar & terminal…. The licence is AGPL-3.0.

When your agent uses it

  • Scenarios: reading cells
  • Highest/lowest values
  • Editing cell values
  • Inserting rows/columns

Example prompts

  • “who has the highest sales in this sheet”
  • “total Q1 revenue”
  • “change B2 to 500”
  • “/xlsx-skill”

Workflow steps

4 steps, taken from the step headings in SKILL.md.

  1. Read: Start with ExcelInspect(summary)
  2. Write: JsSandbox + exceljs
  3. Format Conversion
  4. Common Pitfalls

What it can do on your machine

Read from SKILL.md and the folder at commit f7eccf6. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are javascript).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

XLSX Skill loads about 1.9k tokens when it runs. Until then it costs about 213 tokens; SKILL.md has 326 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~213
When it runs · the whole SKILL.md, loaded when a task matches
~1.9k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from OpenLoaf/OpenLoaf at commit f7eccf6, republished under its AGPL-3.0 licence (© OpenLoaf). 326 words, ~1,948 tokens.

Download SKILL.mdSave it as .claude/skills/xlsx-skill/SKILL.md (or your agent's skills folder).
name
xlsx-skill
description
Unified read / write / stats / recalc / chart capability for Excel / CSV (.xlsx / .xlsm / .csv / .tsv). Trigger scenarios: reading cells, summarizing, grouping, highest/lowest values, total revenue, editing cell values or formulas, inserting rows/columns, adding total rows, inserting charts (bar/line/pie), freezing panes, auto-filter, conditional formatting, CSV ↔ XLSX conversion, building rosters / sales sheets / financial models, diagnosing #REF! / #DIV/0! formula errors, triggering recalculation. Typical phrasings: "who has the highest sales in this sheet", "total Q1 revenue", "change B2 to 500", "add a total row", "create a new roster", "convert csv to xlsx", "freeze the first row", "highlight negatives in column A red". Load this skill whenever the user mentions an .xlsx / .csv file or the final deliverable is a spreadsheet.

XLSX Skill

Read with ExcelInspect; all write / modify / create operations use JsSandbox (preferred library: exceljs, which has broader support for styles / charts / images compared to xlsx/SheetJS); format conversion (including csv ↔ xlsx) can also use DocConvert.

Tool List

ToolResponsibilityRead-only
ExcelInspectRead: summary / values / formulas / style / range / chart-list / defined-namesYes
JsSandboxAll writes: create / update / insert / formula / chart / image / structure / recalc… implemented with exceljsNo
DocConvertcsv ↔ xlsx ↔ html / mdNo

Loading (two steps):

  1. LoadSkill xlsx-skill
  2. ToolSearch(query: "select:ExcelInspect,JsSandbox,DocConvert")

Read on a .xlsx returns only a lightweight summary; all analysis / stats / edit / creation must go through ExcelInspect + JsSandbox.


1. Read: Start with ExcelInspect(summary)

ExcelInspect { action: "summary", filePath: "…" }

Returns sheets[{name, rows, cols, hasFormula, hasChart}]. Then as needed:

  • Read data → ExcelInspect(action="values", sheetName, range)
  • Read formulas → action="formulas"
  • Read styles → action="style", range
  • Check errors → action="errors" — lists #REF! / #DIV/0! / #NAME? etc.

For large sheets, pass range (e.g. "A1:D100") to avoid full-sheet preview truncation.


2. Write: JsSandbox + exceljs

exceljs supports styles / merges / formulas / charts / images / data validation. Handles tens of thousands of rows without issue.

2.1 Demo: Create a sales data sheet (formula total row + frozen header + number format)
js
import ExcelJS from 'exceljs'
const wb = new ExcelJS.Workbook()
const ws = wb.addWorksheet('Q1 Sales')

// Headers
ws.columns = [
  { header: 'Product',  key: 'name',  width: 20 },
  { header: 'Region',   key: 'area',  width: 10 },
  { header: 'Units',    key: 'qty',   width: 10 },
  { header: 'Price ($)', key: 'price', width: 14, style: { numFmt: '$#,##0.00' } },
  { header: 'Revenue ($)', key: 'total', width: 14, style: { numFmt: '$#,##0.00' } },
]
const rows = [
  { name: 'Smart Speaker', area: 'East',  qty: 1240, price: 300 },
  { name: 'Robot Vacuum',  area: 'South', qty: 410,  price: 3000 },
  { name: 'Wireless Earbuds', area: 'North', qty: 860, price: 150 },
]
rows.forEach((r, i) => {
  const excelRow = ws.addRow({ ...r, total: null })
  const rowNum = excelRow.number
  ws.getCell(`E${rowNum}`).value = { formula: `C${rowNum}*D${rowNum}` }
})

// Total row
const totalRow = ws.addRow({
  name: 'Total', area: '',
  qty: { formula: `SUM(C2:C${rows.length + 1})` },
  price: null,
  total: { formula: `SUM(E2:E${rows.length + 1})` },
})
totalRow.font = { bold: true }

// Freeze header + bold header + auto-filter
ws.views = [{ state: 'frozen', ySplit: 1 }]
ws.getRow(1).font = { bold: true }
ws.autoFilter = { from: 'A1', to: `E${rows.length + 1}` }

await wb.xlsx.writeFile('sales_q1.xlsx')
console.log('sales_q1.xlsx written')
2.2 Demo: Add a YoY growth column + conditional formatting (red for negatives)
js
import ExcelJS from 'exceljs'
const wb = new ExcelJS.Workbook()
await wb.xlsx.readFile('sales_q1.xlsx')
const ws = wb.getWorksheet('Q1 Sales')

const last = ws.rowCount
ws.getCell(`F1`).value = 'YoY Growth'
for (let r = 2; r < last; r++) {
  ws.getCell(`F${r}`).value = { formula: `(E${r}-E${r}*0.8)/(E${r}*0.8)` }
  ws.getCell(`F${r}`).numFmt = '0.0%'
}

// Conditional format: F column < 0 → red font
ws.addConditionalFormatting({
  ref: `F2:F${last - 1}`,
  rules: [{
    type: 'cellIs',
    operator: 'lessThan',
    formulae: ['0'],
    style: { font: { color: { argb: 'FFFF0000' } } },
    priority: 1,
  }],
})

await wb.xlsx.writeFile('sales_q1.xlsx')
console.log('YoY + conditional format added')
2.3 Demo: Embed a bar chart image
js
import ExcelJS from 'exceljs'
import fs from 'node:fs/promises'

const wb = new ExcelJS.Workbook()
await wb.xlsx.readFile('sales_q1.xlsx')
const ws = wb.getWorksheet('Q1 Sales')

// exceljs doesn't support addChart natively — use office-chart extension, or
// render a PNG via chartjs-node-canvas and embed it with addImage.
// Example using addImage:

// Assume bar.png was generated by chartjs-node-canvas
const imgId = wb.addImage({ buffer: await fs.readFile('bar.png'), extension: 'png' })
ws.addImage(imgId, { tl: { col: 6, row: 1 }, ext: { width: 480, height: 280 } })
await wb.xlsx.writeFile('sales_q1.xlsx')
console.log('chart image embedded')

For native OOXML charts, use officegen or hand-stitch chart XML — high complexity. For most use cases, "render chart as PNG → addImage" is sufficient.

2.4 Demo: CSV → XLSX with formatting
js
import fs from 'node:fs/promises'
import ExcelJS from 'exceljs'

const csv = await fs.readFile(process.argv[2] ?? 'in.csv', 'utf-8')
const [headerLine, ...dataLines] = csv.trim().split(/\r?\n/)
const headers = headerLine.split(',')

const wb = new ExcelJS.Workbook()
const ws = wb.addWorksheet('Sheet1')
ws.addRow(headers).font = { bold: true }
for (const line of dataLines) {
  ws.addRow(line.split(',').map(v => (isNaN(+v) || v === '' ? v : Number(v))))
}
ws.columns.forEach(c => { c.width = 18 })
ws.views = [{ state: 'frozen', ySplit: 1 }]

await wb.xlsx.writeFile('out.xlsx')
console.log('csv → xlsx done')

Simple csv/xlsx conversion can also use DocConvert(from="csv", to="xlsx") without writing code.

2.5 Demo: Diagnose formula errors
js
import ExcelJS from 'exceljs'
const wb = new ExcelJS.Workbook()
await wb.xlsx.readFile('in.xlsx')
const errs = []
for (const ws of wb.worksheets) {
  ws.eachRow((row, rn) => {
    row.eachCell((cell, cn) => {
      // exceljs reads error cells as { error: '#REF!' }
      if (cell.value && typeof cell.value === 'object' && cell.value.error) {
        errs.push({ sheet: ws.name, cell: cell.address, error: cell.value.error, formula: cell.formula })
      }
    })
  })
}
console.log(JSON.stringify(errs, null, 2))

3. Format Conversion

DocConvert(from="csv",  to="xlsx", sourcePath="…")
DocConvert(from="xlsx", to="csv",  sourcePath="…")
DocConvert(from="xlsx", to="html", sourcePath="…")

4. Common Pitfalls

SymptomCauseFix
Formula saved as a stringUsing cell.value = '=A1+B1'Use { formula: 'A1+B1' } instead
CJK column width too narrowDefault width calculated in ASCII charactersManually set column.width = 20
Numbers display in scientific notation after openMore than 11 digitscell.numFmt = '0' or '@' (text)
File reports "damaged" on openFormula syntax error / circular referenceRun ExcelInspect(errors) first; or write static values before substituting formulas

To patch a script: JsSandbox(action="edit-and-run", scriptPath=…, edits=[…]) — only pass the diff.

© OpenLoaf, AGPL-3.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in apps/server/src/ai/builtin-skills/xlsx/en of OpenLoaf/OpenLoaf.

Open the folder on GitHubat commit f7eccf6

Compare with similar skills

XLSX Skill next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

XLSX Skill compared with similar skills
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XLSX Skill this skillOpenLoaf/OpenLoaf108—~1.9kAutomated safety check: PassAGPL-3.0
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Instrument Data To Allotropeaws-samples/amazon-bedrock-agents-healthcare-lifesciences2742 repos~2.7kAutomated safety check: PassApache-2.0
Markitshift-labs-ai/markit1.3k—~299Automated safety check: PassMIT
Convert Fileduckdb/duckdb-skills6041 repos~720Automated safety check: NotesMIT
Research Integrity Auditxuzhougeng/wisp-science1k—~2.6kAutomated safety check: PassAGPL-3.0

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Works with

Questions about XLSX Skill

What does XLSX Skill do?

Unified read / write / stats / recalc / chart capability for Excel / CSV (.xlsx / .xlsm / .csv / .tsv). XLSX Skill is an agent skill from OpenLoaf/OpenLoaf.tsv).

When should I use XLSX Skill?

XLSX Skill fits situations like: scenarios: reading cells; highest/lowest values; editing cell values; inserting rows/columns.

How do I install XLSX Skill in Claude Code?

Run `npx skills add OpenLoaf/OpenLoaf --skill xlsx-skill -a claude-code`. Or copy the skill folder (apps/server/src/ai/builtin-skills/xlsx/en in OpenLoaf/OpenLoaf) into .claude/skills/xlsx-skill in your project. Claude Code loads it when a task matches its description.

How do I install XLSX Skill in Codex?

Run `npx skills add OpenLoaf/OpenLoaf --skill xlsx-skill -a codex`. Or copy the skill folder (apps/server/src/ai/builtin-skills/xlsx/en in OpenLoaf/OpenLoaf) into .agents/skills/xlsx-skill in your project. Codex loads it when a task matches its description.

Can I use XLSX Skill in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add OpenLoaf/OpenLoaf --skill xlsx-skill -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/xlsx-skill, .gemini/skills/xlsx-skill, .github/skills/xlsx-skill and .opencode/skills/xlsx-skill in your project.

What does XLSX Skill need to run?

SKILL.md names no scripts, command-line tools or credentials: XLSX Skill is instructions for the agent only.

Does XLSX Skill access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is XLSX Skill safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does XLSX Skill use?

XLSX Skill is published under the AGPL-3.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does XLSX Skill use?

About 1.9k tokens (SKILL.md is roughly 7.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to XLSX Skill?

Skills that share tags, products or a category with XLSX Skill: Data Table Manager (n8n-io/n8n, 207k stars), Instrument Data To Allotrope (aws-samples/amazon-bedrock-agents-healthcare-lifesciences, 274 stars), Markit (shift-labs-ai/markit, 1.3k stars) and Convert File (duckdb/duckdb-skills, 604 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains XLSX Skill?

OpenLoaf (a GitHub organization) maintains it in OpenLoaf/OpenLoaf, which has 108 GitHub stars. The repository holds 33 skills in this directory. The repository was last updated on May 14, 2026.

Source: OpenLoaf/OpenLoaf on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.