xlsx

xlsx is a skill for Claude Code, Codex from AtomicBot-ai/atomic-agent. It costs 44 tokens per session (898 once invoked), scanned A, original, MIT.

A tool for creating and editing Excel .xlsx workbooks using Python and the openpyxl library. It can work with sheets, cells, formulas, and basic formatting.

In plain words
What is it for?
It is for generating workbooks, writing or changing cell values, adding formulas, and applying basic formatting.
Why use it?
It automates spreadsheet creation and updates instead of requiring someone to edit cells by hand.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/atomicbot-ai/atomic-agent/xlsx
Any agent
npx skills add AtomicBot-ai/atomic-agent --skill xlsx
Clone the repo
git clone --depth 1 https://github.com/AtomicBot-ai/atomic-agent

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for xlsx

README.md
[![agentmods](https://agentmods.dev/badge/skills/atomicbot-ai/atomic-agent/xlsx.svg)](https://agentmods.dev/skills/atomicbot-ai/atomic-agent/xlsx)
Your own site
<a href="https://agentmods.dev/skills/atomicbot-ai/atomic-agent/xlsx"><img src="https://agentmods.dev/badge/skills/atomicbot-ai/atomic-agent/xlsx.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 898 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00044 $0.00898
Opus 5 $0.00022 $0.00449
Sonnet 5 $0.00009 $0.00180
Haiku 4.5 $0.00004 $0.00090

Measured 4d ago against content hash 88e8558f1911, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

xlsx scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

starter-skills/xlsx/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

xlsx

Create and modify .xlsx workbooks with the openpyxl Python library. Reading an existing spreadsheet to plain text is best done with the built-in os.fs.read_document tool (no install). Use the scripts below to write: new workbooks, cell values, formulas, and basic formatting.

The pattern is python3 -c "<inline script>" (or python3 script.py for longer logic). Keep scripts short and idempotent; always write to a fresh output path.

Setup health check (run first, every session)

Verify with one solo step:

[{ "tool": "os.shell.run", "args": { "cmd": "python3", "args": ["-c", "import openpyxl; print(openpyxl.__version__)"] } }]

Outcome map:

  • exit 0 + version → ready, proceed.
  • ModuleNotFoundError: openpyxl → enter Setup playbook → "openpyxl missing".
  • command not found: python3 → reply that Python 3 is required and stop.

Setup playbook (when prerequisites are missing)

openpyxl missing

Reply (solo reply step):

"The openpyxl library is not installed. I can install it: python3 -m pip install --user openpyxl. Install it?"

On yes:

[{ "tool": "os.shell.run", "args": { "cmd": "python3", "args": ["-m", "pip", "install", "--user", "openpyxl"] } }]

If pip is externally managed (PEP 668), use pipx run --spec openpyxl python or a venv; ask the user which they prefer.

When to use

  • "Create an Excel file with these rows", "build a budget spreadsheet".
  • "Add a column / formula", "update cell B2", "add a second sheet".
  • Generating reports/exports as .xlsx.

When NOT to use

  • Reading an .xlsx to summarise — use os.fs.read_document.
  • CSV-only work — prefer plain os.fs.write with comma-separated text.
  • Charts / pivot tables / macros — out of scope on v1.

Common operations

Create a workbook with a header row and two data rows:

[{ "tool": "os.shell.run", "args": { "cmd": "python3", "args": ["-c", "import openpyxl; wb=openpyxl.Workbook(); ws=wb.active; ws.title='Report'; ws.append(['Name','Amount']); ws.append(['Coffee',4.5]); ws.append(['Tea',3]); ws['B4']='=SUM(B2:B3)'; wb.save('report.xlsx'); print('wrote report.xlsx')"] } }]

Read the full file on GitHub · 86 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 86 lines · 44 tokens per session scan A 88e8558f1911

Subscribe to this mod's changes

xlsx is a skill published in the GitHub repository AtomicBot-ai/atomic-agent (2,438 stars, last pushed yesterday), licensed MIT. It adds 44 tokens to every session and 898 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.