New: 98,000+ skills indexed from GitHub repos with 100+ stars · every skill safety-checkedBrowse top skillsTop skills
Esc to closeBrowse all skills
Submit a skillBrowse skills
Submit a skillBrowse skills

Agent skill

Spreadsheet Authoring

by vellum-ai in vellum-ai/vellum-assistant

Create and edit Excel spreadsheets (.xlsx) whose formulas carry their computed values, so sums and totals show in every viewer, plus date and time formats, recalculating and verifying an existing…

MITAuto-check passedDocuments & Office

Install Spreadsheet Authoring

skills CLI
$ npx skills add vellum-ai/vellum-assistant --skill spreadsheet-authoring -a claude-code

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

GitHub CLI
$ gh skill install vellum-ai/vellum-assistant spreadsheet-authoring --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/vellum-ai/vellum-assistant.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/spreadsheet-authoring .claude/skills/spreadsheet-authoring && 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
spreadsheet-authoring
GitHub stars
1.4k
Token cost
~1.6k tokens
SKILL.md length
637 words
Files
1
Skills in repo
108
Repo updated
First seen
Licence
MIT

At a glance

Create and edit Excel spreadsheets (.xlsx) whose formulas carry their computed values, so sums and totals show in every viewer, plus date and time formats, recalculating and verifying an existing…

  • Tasks that involve Excel spreadsheets
  • SKILL.md covers A formula is stored with the…, Install the two packages first, Writing a new workbook and Editing a workbook that…, plus 2 more sections
  • Calls python3, pip and soffice

What it does

Spreadsheet Authoring is an agent skill from vellum-ai/vellum-assistant. Create and edit Excel spreadsheets (.xlsx) whose formulas carry their computed values, so sums and totals show in every viewer, plus date and time formats, recalculating and verifying an existing workbook.

Its SKILL.md is about 1.6k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts. Compatibility notes: Needs Python in the assistant's environment with the XlsxWriter package for writing and openpyxl for verifying. Works on desktop and web.

It sits in Documents & Office, covering Excel spreadsheets. It works with Microsoft Excel, Python and openpyxl. The repository describes itself as: An AI Assistant that’s easy to setup, does your work 24/7, knows your preferences and gets better over time. The licence is MIT.

When your agent uses it

  • Tasks that involve Excel spreadsheets

Example prompts

  • “/spreadsheet-authoring”

Requirements

  • Python 3
  • Compatibility (from SKILL.md): Needs Python in the assistant's environment with the XlsxWriter package for writing and openpyxl for verifying. Works on desktop and web.

What it can do on your machine

Read from SKILL.md and the folder at commit 844117a. 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

    Shell commands in SKILL.md call:

    • python3
    • pip
    • soffice

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

  • Network

    No URLs in SKILL.md. Its commands use pip, which can reach the network depending on how they are called.

    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.

  • Compatibility

    Needs Python in the assistant's environment with the XlsxWriter package for writing and openpyxl for verifying. Works on desktop and web.

    From compatibility in the SKILL.md frontmatter.

Context cost

Spreadsheet Authoring loads about 1.6k tokens when it runs. Until then it costs about 57 tokens; SKILL.md has 637 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~57
When it runs · the whole SKILL.md, loaded when a task matches
~1.6k

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 vellum-ai/vellum-assistant at commit 844117a, republished under its MIT licence (© vellum-ai). 637 words, ~1,636 tokens.

Download SKILL.mdSave it as .claude/skills/spreadsheet-authoring/SKILL.md (or your agent's skills folder).
name
spreadsheet-authoring
description
Create and edit Excel spreadsheets (.xlsx) whose formulas carry their computed values, so sums and totals show in every viewer, plus date and time formats, recalculating and verifying an existing workbook.
compatibility
Needs Python in the assistant's environment with the XlsxWriter package for writing and openpyxl for verifying. Works on desktop and web.
metadata.emoji
📊

Spreadsheet Authoring

Write workbooks whose numbers are visible everywhere they are opened.

A formula is stored with the value it produced

An .xlsx cell holding a formula stores two things: the formula text, and the value that formula last produced. Excel fills the value in when it saves. openpyxl writes none, because it has no formula engine.

Anything that does not run a formula engine shows what the file stores. Chat file previews, Quick Look, Google Drive previews, and mail previews all read the stored value, so a workbook written by openpyxl shows =SUM(C2:C7) where the total should be, and a summary sheet of formulas comes out blank.

So: write the computed value next to every formula. Compute it in Python, where the data already is.

Install the two packages first

Both come from PyPI and neither is there by default. Run this once at the start of the task; the import check makes it a no-op when they are already installed.

bash
python3 -c "import xlsxwriter, openpyxl" 2>/dev/null \
  || pip install --user --quiet XlsxWriter==3.2.9 openpyxl==3.1.5 \
  || pip install --user --quiet --break-system-packages XlsxWriter==3.2.9 openpyxl==3.1.5

Use pip, not python3 -m pip. Some environments mark the system Python as externally managed, and the second form is refused there outright. If both attempts fail, build a virtualenv somewhere that persists (python3 -m venv .venv), install into it, and run the scripts below with .venv/bin/python.

Writing a new workbook

Use XlsxWriter. write_formula(row, col, formula, format, value) takes the value as its last argument, which is the whole point.

python
import datetime

import xlsxwriter

rows = [
    ("Widget", datetime.date(2026, 1, 5), 120, 4.50),
    ("Gadget", datetime.date(2026, 1, 6), 80, 12.00),
    ("Doohickey", datetime.date(2026, 1, 7), 45, 7.25),
]
last = len(rows) + 1

book = xlsxwriter.Workbook("sales.xlsx")
bold = book.add_format({"bold": True})
money = book.add_format({"num_format": "#,##0.00"})
day = book.add_format({"num_format": "yyyy-mm-dd"})

sales = book.add_worksheet("Sales")
sales.write_row(0, 0, ["Item", "Date", "Units", "Unit price", "Total"], bold)
for index, (item, sold_on, units, price) in enumerate(rows, start=1):
    sales.write_string(index, 0, item)
    sales.write_datetime(index, 1, sold_on, day)
    sales.write_number(index, 2, units)
    sales.write_number(index, 3, price, money)
    line = index + 1
    sales.write_formula(index, 4, f"=C{line}*D{line}", money, units * price)

summary = book.add_worksheet("Summary")
summary.write_string(0, 0, "Revenue", bold)
summary.write_formula(
    0, 1, f"=SUM(Sales!E2:E{last})", money, sum(u * p for _, _, u, p in rows)
)
summary.write_string(1, 0, "Items sold", bold)
summary.write_formula(1, 1, f"=COUNTA(Sales!A2:A{last})", None, len(rows))

book.close()

Every formula above carries its result, including the ones reaching across sheets. Pass None as the format when the cell needs no number format.

Dates and times need a number format

A date in an .xlsx file is a number. Without a format it shows as a serial such as 46027. Pass a format to write_datetime:

  • yyyy-mm-dd for a date
  • hh:mm:ss for a time of day
  • yyyy-mm-dd hh:mm:ss for both

Build each one with book.add_format({"num_format": "yyyy-mm-dd"}) and reuse it for the whole column.

Show full SKILL.md (330 more words)Show less

Editing a workbook that already exists

XlsxWriter only writes new files, and openpyxl does not preserve cached results. A cell's formula and the value it produced are two separate things in the file, and openpyxl holds only one of them: loaded the default way it keeps the formula and discards the value, loaded with data_only=True it keeps the value and discards the formula. A save writes back what it kept. So saving an existing workbook with openpyxl leaves every formula in it without a result, including the ones the edit never touched, and the totals go blank in a preview.

Three ways through it, best first:

  • Rebuild the file with XlsxWriter from the data, writing every formula with its value as above. This is the only path that guarantees the result, and it is usually cleaner than patching.

  • Save with openpyxl, then hand the file to a formula engine to fill the values back in. LibreOffice computes the formulas it finds without results and writes them out when it saves:

    bash
    soffice --headless --convert-to xlsx --outdir out/ book.xlsx

    --outdir has to differ from the input's directory, and LibreOffice is not installed everywhere. Verify the output rather than assuming it worked.

  • Write the literal computed value instead of a formula, when the user does not need the formula itself.

Whichever path, run the check below on the file you are about to send.

Verify before sharing

Read the file back and check that every formula cell has a cached value. A None means the cell will look empty in a preview.

python
from openpyxl import load_workbook

formulas = load_workbook("sales.xlsx")
values = load_workbook("sales.xlsx", data_only=True)
for sheet in formulas.worksheets:
    for row in sheet.iter_rows():
        for cell in row:
            if cell.data_type == "f":
                cached = values[sheet.title][cell.coordinate].value
                if cached is None:
                    print(f"no value: {sheet.title}!{cell.coordinate}")

Silence means every formula carries its value. Open the preview once as well, to see what the user will see.

What to tell the user

Say that the totals are written into the file, so they show up in a preview, and that Excel recalculates them from the formulas as soon as it opens the workbook. If a formula had to become a plain number, say which cells and why.

© vellum-ai, MIT. 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 skills/spreadsheet-authoring of vellum-ai/vellum-assistant.

Open the folder on GitHubat commit 844117a

Compare with similar skills

Spreadsheet Authoring 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.

Spreadsheet Authoring compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Spreadsheet Authoring this skillvellum-ai/vellum-assistant1.4k—~1.6kAutomated safety check: PassMIT
Excel Workbook EditorTokenRhythm/opensquilla7.1k—~1.6kAutomated safety check: PassApache-2.0
Kimi XLSXthvroyal/kimi-skills238—~9.5kAutomated safety check: PassNone
Office XLSXopen-octo/octo-agent125—~1.8kAutomated safety check: NotesMIT
Cc Streaming Export Safetydoccker/cc-use-exp1.1k—~2.2kAutomated safety check: PassCustom licence
XLSXnexus-research-lab/nexus151—~501Automated safety check: PassApache-2.0

Similar skills

  • Excel Workbook Editor

    TokenRhythm/opensquilla

    Inspects, edits in place or creates Microsoft Excel .xlsx workbooks with openpyxl, treating each cell as a typed number, string, datetime or formula value.

    7.1k GitHub stars~1.6k tokensUpdated today
    Documents & OfficeAuto-check passed

  • Kimi XLSX

    thvroyal/kimi-skills

    Specialized utility for advanced manipulation, analysis, and creation of spreadsheet files, including (but not limited to) XLSX, XLSM, CSV formats.

    238 GitHub stars~9.5k tokensUpdated 6 mo ago
    Documents & OfficeAuto-check passed

  • Office XLSX

    open-octo/octo-agent

    Create, read, and edit Excel (.xlsx) spreadsheets programmatically with openpyxl — cell values, formulas, styling (fonts/fills/borders/alignment/number formats), merged cells, multiple sheets…

    125 GitHub stars~1.8k tokensUpdated today
    Documents & OfficeAuto-check: notes

  • Cc Streaming Export Safety

    doccker/cc-use-exp

    当实现用户驱动的大文件导出或批量序列化（Excel/CSV/JSON/JSONL/PDF，数据量未知或超过 1 万行/10 MB）时触发；普通小文件下载、静态资源下载、非导出 Writer/Report 类不触发。防止 OOM、临时文件残留、同步导出阻塞 HTTP 线程和表格公式注入。

    1.1k GitHub stars~2.2k tokensUpdated 1 mo ago
    Documents & OfficeAuto-check passed

  • XLSX

    nexus-research-lab/nexus

    只要电子表格文件（.xlsx、.xlsm、旧版 .xls、.csv、.tsv）是任务的主要输入或输出，或者需要 被打开、读取、创建、修改，就使用本 Skill。也适用于公式、格式、图表、数据清洗和表格格式转换。

    151 GitHub stars~501 tokensUpdated today
    Documents & OfficeAuto-check passed

  • Office XLSX

    singula-ai/alego

    Read, create, and modify Excel workbooks (.xlsx), including data, formulas, formatting, and pandas analysis.

    109 GitHub starsUsed in 1 repo~2.3k tokens
    Documents & OfficeAuto-check passed

More from vellum-ai/vellum-assistant

All 108 skills in this repo

  • Vellum GitHub App Setup

    vellum-ai/vellum-assistant

    Create and configure a GitHub App so the assistant can push commits, open PRs, and comment under its own bot identity.

    1.4k GitHub stars~3.1k tokensUpdated yesterday
    Auto-check passed

  • Discord App Setup

    vellum-ai/vellum-assistant

    Connect a Discord bot to the assistant via the Discord Gateway with guided application creation and intent configuration

    1.4k GitHub stars~4.2k tokensUpdated yesterday
    Auto-check passed

  • Sentry App Setup

    vellum-ai/vellum-assistant

    Create and configure a Sentry internal integration so the assistant can manage issues, alerts, and releases under its own identity

    1.4k GitHub stars~1.3k tokensUpdated yesterday
    Auto-check passed

  • Memory Corpus Ingest

    vellum-ai/vellum-assistant

    Ingest a large dataset into memory as a skimmed map. An agent skill from vellum-ai/vellum-assistant.

    1.4k GitHub stars~3k tokensUpdated yesterday
    Auto-check: notes

  • Plugin Builder

    vellum-ai/vellum-assistant

    A skill your agent uses when the user wants to build, scaffold, ship, or edit a Vellum plugin that bundles multiple surfaces (hooks, tools, skills, and more) into one installable package.

    1.4k GitHub stars~3.1k tokensUpdated yesterday
    Auto-check passed

  • Slack App Setup

    vellum-ai/vellum-assistant

    Connect a Slack app to the Vellum Assistant via Socket Mode.

    1.4k GitHub stars~2.5k tokensUpdated yesterday
    Auto-check: warnings

Works with

Categories

Questions about Spreadsheet Authoring

What does Spreadsheet Authoring do?

Create and edit Excel spreadsheets (.xlsx) whose formulas carry their computed values, so sums and totals show in every viewer, plus date and time formats, recalculating and verifying an existing…. Spreadsheet Authoring is an agent skill from vellum-ai/vellum-assistant.xlsx) whose formulas carry their computed values, so sums and totals show in every viewer, plus date and time formats, recalculating and verifying an existing workbook.

When should I use Spreadsheet Authoring?

Spreadsheet Authoring fits situations like: tasks that involve Excel spreadsheets.

How do I install Spreadsheet Authoring in Claude Code?

Run `npx skills add vellum-ai/vellum-assistant --skill spreadsheet-authoring -a claude-code`. Or copy the skill folder (skills/spreadsheet-authoring in vellum-ai/vellum-assistant) into .claude/skills/spreadsheet-authoring in your project. Claude Code loads it when a task matches its description.

How do I install Spreadsheet Authoring in Codex?

Run `npx skills add vellum-ai/vellum-assistant --skill spreadsheet-authoring -a codex`. Or copy the skill folder (skills/spreadsheet-authoring in vellum-ai/vellum-assistant) into .agents/skills/spreadsheet-authoring in your project. Codex loads it when a task matches its description.

Can I use Spreadsheet Authoring 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 vellum-ai/vellum-assistant --skill spreadsheet-authoring -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/spreadsheet-authoring, .gemini/skills/spreadsheet-authoring, .github/skills/spreadsheet-authoring and .opencode/skills/spreadsheet-authoring in your project.

What does Spreadsheet Authoring need to run?

Going by SKILL.md and its folder, Spreadsheet Authoring needs the command-line tools its instructions call (python3, pip and soffice). Our summary lists: Python 3. Compatibility (from SKILL.md): Needs Python in the assistant's environment with the XlsxWriter package for writing and openpyxl for verifying. Works on desktop and web..

Does Spreadsheet Authoring access the network?

SKILL.md contains no URLs. Its commands use pip, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Spreadsheet Authoring 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 Spreadsheet Authoring use?

Spreadsheet Authoring is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Spreadsheet Authoring use?

About 1.6k tokens (SKILL.md is roughly 6.5k 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 Spreadsheet Authoring?

Skills that share tags, products or a category with Spreadsheet Authoring: Excel Workbook Editor (TokenRhythm/opensquilla, 7.1k stars), Kimi XLSX (thvroyal/kimi-skills, 238 stars), Office XLSX (open-octo/octo-agent, 125 stars) and Cc Streaming Export Safety (doccker/cc-use-exp, 1.1k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Spreadsheet Authoring?

vellum-ai (a GitHub organization) maintains it in vellum-ai/vellum-assistant, which has 1,400 GitHub stars. The repository holds 108 skills in this directory. The repository was last updated on October 9, 2026.

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