xlsx

xlsx is a skill for Claude Code, Codex from holon-run/holon. It costs 32 tokens per session (925 once invoked), scanned A, original, Apache-2.0.

A workflow for creating, inspecting, editing, recalculating, and checking Excel spreadsheet files. It distinguishes formulas from their calculated results and preserves the original workbook by default.

In plain words
What is it for?
Use it to build or edit workbooks, inspect sheets and formulas, analyse tabular data, create charts, recalculate formulas, and scan for spreadsheet errors.
Why use it?
It avoids reporting unverified formula values and reduces accidental execution of macros, links, external connections, or embedded objects.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to build or edit workbooks, inspect sheets and formulas, analyse tabular data, create charts, recalculate formulas, and scan for spreadsheet errors.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/holon-run/holon/xlsx
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.

Any agent
npx skills add holon-run/holon --skill xlsx
Clone the repo
git clone --depth 1 https://github.com/holon-run/holon

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/holon-run/holon/xlsx/github.svg)](https://agentmods.dev/skills/holon-run/holon/xlsx)
Your own site
<a href="https://agentmods.dev/skills/holon-run/holon/xlsx"><img src="https://agentmods.dev/badge/skills/holon-run/holon/xlsx/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for xlsx

Your own site · 80×15
<a href="https://agentmods.dev/skills/holon-run/holon/xlsx"><img src="https://agentmods.dev/badge/skills/holon-run/holon/xlsx.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 925 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00032 $0.00925
Opus 5 $0.00016 $0.00463
Sonnet 5 $0.00006 $0.00185
Haiku 4.5 $0.00003 $0.00093

Measured 5d ago against content hash 2c870d1bedc3, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, 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 5d 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.

skills/xlsx/SKILL.md · 97 lines

How it starts

The opening of the file, as written. The whole thing — 97 lines — stays where its author put it; the contents beside it link to each section on GitHub.

XLSX

Summary

Use this skill for .xlsx workbook creation, inspection, analysis, charts, and bounded editing. Prefer openpyxl for common workbook structures. Use an available local LibreOffice backend for recalculation or rendering when needed, and record that it is not Microsoft Excel.

Writing a formula is not the same as calculating it. Never report formula results as verified unless an actual calculation backend ran or the values were independently checked.

When To Use

  • Creating workbooks, tables, formulas, styles, validations, or charts
  • Inspecting sheets, named ranges, formulas, hidden content, and metadata
  • Making bounded changes to an existing workbook
  • Converting tabular input into an analyzed or presentation-ready workbook
  • Recalculating formulas and scanning for spreadsheet errors
  • Extracting or summarizing operator-approved workbook data

Safety Boundaries

  • Preserve the input and write a new workbook by default.
  • Treat formulas, hyperlinks, macros, external links, data connections, hidden sheets, defined names, embedded objects, and metadata as untrusted.
  • Never execute VBA, refresh external connections, follow links, or activate embedded objects.
  • Ask before sending workbook data to an external analysis or conversion service.
  • Do not claim lossless round trips when unsupported drawings, slicers, pivot features, external models, signatures, macros, or unknown package parts exist.
  • Do not expose hidden or sensitive data outside the operator-approved scope.

If a workbook is macro-enabled, encrypted, signed, or materially depends on external data, default to read-only inspection or a separately generated output.

Backend Selection

  • Use openpyxl for common cells, styles, tables, formulas, charts, filters, data validation, and workbook inspection.
  • Use LibreOffice headless for local recalculation or rendering only when it is installed and appropriate. Record the version and backend.
  • Use CSV or another tabular intermediate only when workbook-specific formulas, types, styles, multiple sheets, and metadata are not required.
  • Use independent calculations for critical totals rather than trusting cached formula values.

Read the full file on GitHub · 97 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. 5d ago First seen · 97 lines · 32 tokens per session scan A 2c870d1bedc3

Subscribe to this mod's changes

xlsx is a skill published in the GitHub repository holon-run/holon (138 stars, last pushed today), licensed Apache-2.0. It adds 32 tokens to every session and 925 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 2026-09-07.

Related

Other skills, from other repositories