excel-author

excel-author is a skill for Claude Code, Codex from NousResearch/hermes-agent. It costs 16 tokens per session (2,367 once invoked), scanned A, original, MIT.

A guide for creating auditable Excel financial workbooks with Python's openpyxl library. Auditable means another person can trace inputs, formulas, and linked values through the file.

In plain words
What is it for?
Use it to build one-model-per-file workbooks with formula-driven calculations, sensitivity tables, and conventions that distinguish hardcoded inputs, formulas, and external links.
Why use it?
It helps keep financial models clear and reviewable by visually separating typed inputs, calculations, and links to other sheets or files.

Skill for Claude CodeCodex

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

Needs its repository: it runs a file that does not travel with it, so clone the repository first. The line is libreoffice --headless --calc --convert-to xlsx ./out/model.xlsx --outdir ./out/.

Good fit Use it to build one-model-per-file workbooks with formula-driven calculations, sensitivity tables, and…

Compare 6 skills from other repositories ↓
About the project

Hermes Agent is an AI assistant that learns from its use by creating and improving skills, retaining knowledge, searching past conversations, and adapting to its users. It is for people who want to run an agent through a terminal or messaging platforms while connecting it to different AI models and scheduled tasks.

NousResearch/hermes-agent · 242,093 stars · on GitHub · hermes-agent.nousresearch.com

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/NousResearch/hermes-agent
agentmods
npx agentmods add skills/nousresearch/hermes-agent/excel-author

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 excel-author

README.md
[![agentmods](https://agentmods.dev/badge/skills/nousresearch/hermes-agent/excel-author.svg)](https://agentmods.dev/skills/nousresearch/hermes-agent/excel-author)
Your own site
<a href="https://agentmods.dev/skills/nousresearch/hermes-agent/excel-author"><img src="https://agentmods.dev/badge/skills/nousresearch/hermes-agent/excel-author.svg" alt="Measured on agentmods" height="20"></a>
Per session 16 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,367 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 $0.00016 $0.02367
Opus 5 $0.00008 $0.01184
Sonnet 5 $0.00003 $0.00473
Haiku 4.5 $0.00002 $0.00237

Measured 7d ago against content hash f0228fe29411, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

excel-author 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 7d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/recalc.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Origin

Copies of this mod

6 near-identical copies found in the catalogue:

optional-skills/finance/excel-author/SKILL.md · 245 lines

How it starts

The opening of the file, as written. The whole thing — 245 lines — stays where its author put it; the contents beside it link to each section on GitHub.

excel-author

Produce an .xlsx file on disk using openpyxl. Follow the banker-grade conventions below so the model is auditable, flexible, and reviewable by someone other than the person who built it.

Adapted from Anthropic's xlsx-author and audit-xls skills in the anthropics/financial-services repo. The MCP / Office-JS / Cowork-specific branches of the originals are dropped — this skill assumes headless Python.

Output contract

  • Write to ./out/<name>.xlsx. Create ./out/ if it does not exist.
  • Return the relative path in your final message so downstream tools can pick it up.
  • One logical model per file. Do not append to an existing workbook unless explicitly asked.

Setup

pip install "openpyxl>=3.0"

Core conventions (non-negotiable)

Blue / black / green cell color

  • Blue (Font(color="0000FF")) — hardcoded input a human entered. Revenue drivers, WACC inputs, terminal growth, market data.
  • Black (default) — formula. Every derived cell is a live Excel formula.
  • Green (Font(color="006100")) — link to another sheet or external file.

A reviewer can then scan the sheet and immediately see what's an assumption vs. what's computed.

Formulas over hardcodes

Every calculation cell MUST be a formula string, never a number computed in Python and pasted as a value.

# WRONG — silent bug waiting to happen
ws["D20"] = revenue_prior_year * (1 + growth)

# CORRECT — flexes when the user changes the assumption
ws["D20"] = "=D19*(1+$B$8)"

The only hardcoded numbers permitted:

  1. Raw historical inputs (actual revenues, reported EBITDA, etc.)
  2. Assumption drivers the user is meant to flex (growth rates, WACC inputs, terminal g)
  3. Current market data (share price, debt balance) — with a cell comment documenting source + date

If you catch yourself computing a value in Python and writing the result, stop.

Named ranges for cross-sheet references

Use named ranges for any figure referenced from another sheet, a deck, or a memo.

Read the full file on GitHub · 245 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 245 lines · 16 tokens per session scan A f0228fe29411

Subscribe to this mod's changes

excel-author is a skill published in the GitHub repository NousResearch/hermes-agent (242,093 stars, last pushed yesterday), licensed MIT. It adds 16 tokens to every session and 2,367 once invoked, about $0.0001 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.

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