> ## Content Index
> Fetch the complete content index at: https://dangraf.io/llms.txt
> Use this file to discover other available public pages before exploring further.

# Least-privilege AI tooling: the SIGNALS MCP server
- URL: https://dangraf.io/work/signals-mcp/
- Published: 2026-10-09T14:13:08.000Z
- Updated: 2026-10-09T14:34:09.000Z
- Description: Giving an AI assistant read/write access to exactly one spreadsheet and nothing else.
- Author: Dan Graf
- Tags: AI, #work, #Import 2026-10-09 15:24

SIGNALS is Earthchain's monthly newsletter for sustainability teams, sharing practical lessons on using data and automation to support better decisions and real action.

![The September 2026 edition, ](https://dangraf.io/content/images/2026/10/signals-edition.jpg)

The September 2026 edition, "Who's doing the chasing?"

Each edition is planned and written in a Google Sheet. I wanted Claude to draft and edit editions directly, without giving an AI agent the keys to the whole Google account. That account also holds a CRM sheet with customer names, emails and phone numbers.

## The approach

Instead of a general-purpose Sheets integration, I built a small [Model Context Protocol](https://modelcontextprotocol.io/?ref=dangraf.io) server that is deliberately narrow:

- It's bound to a single, hard-coded spreadsheet ID. No tool accepts an ID as input.
- It holds only the Sheets scope, not Drive, so it can't list or open other files.
- Its tools are shaped around the editorial job (list editions, read an edition, write a field, lint copy against the house style), not around raw cell access.

## Why it matters

This is the pattern I recommend to teams adopting AI agents: design the tool surface around the task, and make the dangerous thing impossible rather than merely discouraged.