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excel-mcp-server: Instructions file for Claude Code

CLAUDE.md

excel-mcp-server CLAUDE.md is an instructions file for Claude Code from Samcil/excel-mcp-server. It costs 827 tokens per session, scanned A, a copy of excel-mcp-server CLAUDE.md, MIT.

A project instruction file for an MCP server that lets AI assistants read and modify Microsoft Excel files programmatically.

In plain words
What is it for?
Use it when developing or testing the Go and TypeScript code that supports live Excel on Windows or cross-platform spreadsheet files.
Why use it?
It gives coding agents the project overview, architecture, development commands, and tests needed to change the server safely.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions CLAUDE.md; mentions Claude Code.

This is Samcil/excel-mcp-server's own configuration. It tells Claude Code how to work on excel-mcp-server itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything excel-mcp-server configures →

not rated 0repo 2mo ago A scan 827 tokens copy · 97% MIT
View source ↗ Samcil/excel-mcp-server
Reuse

Borrowing it

Nothing to install: this file belongs to Samcil/excel-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/Samcil/excel-mcp-server/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/Samcil/excel-mcp-server

Made for: Claude Code.

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Per session 827 This file is loaded in full into every session.
When invoked 827 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 97% copy Near-identical to another mod 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 $0.00827 $0.00827
Opus 5.5 $0.00331 $0.00331
Sonnet 5.5 $0.00165 $0.00165
Haiku 4.5 $0.00083 $0.00083

Measured 1mo ago against content hash 24ac5befa5f7, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

excel-mcp-server CLAUDE.md 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 1mo 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.

Origin

This is a copy

97% identical to excel-mcp-server CLAUDE.md — 20 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

CLAUDE.md · 123 lines

How it starts

The opening of the file, as written. The whole thing — 123 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

This is an Excel MCP (Model Context Protocol) Server that enables AI assistants to interact with Microsoft Excel files. It provides a bridge between AI models and Excel spreadsheets for programmatic data manipulation.

Development Commands

Build and Development

npm run build     # Build Go binaries + compile TypeScript
npm run watch     # Watch TypeScript files for changes
npm run debug     # Debug with MCP inspector

Testing

go test ./...                           # Run all Go tests
go test ./internal/tools -v             # Run specific package tests
go test -run TestReadSheetData ./internal/tools  # Run specific test

Linting and Formatting

go fmt ./...      # Format Go code
go vet ./...      # Vet Go code for issues

Architecture

Core Components

Dual Backend Architecture: The server supports two Excel backends:

  • Windows: OLE automation for live Excel interaction (excel_ole.go)
  • Cross-platform: Excelize library for file operations (excel_excelize.go)

Key Interfaces:

  • ExcelInterface in internal/excel/excel.go - Unified Excel operations API
  • Tool interface in internal/tools/ - MCP tool implementations

Entry Points:

  • cmd/office-mcp-server/main.go - Go binary entry point
  • launcher/launcher.ts - Cross-platform launcher that selects appropriate binary

Tool System

MCP tools are implemented in internal/tools/:

  • excel_describe_sheets - List worksheets and metadata
  • excel_read_sheet - Read sheet data with pagination
  • excel_write_to_sheet - Write data to sheets
  • excel_create_table - Create Excel tables
  • excel_copy_sheet - Copy sheets between workbooks
  • excel_screen_capture - Windows-only screenshot functionality

Pagination System

Large datasets are handled through configurable pagination:

  • Default limit: 4000 cells
  • Configurable via EXCEL_MCP_PAGING_CELLS_LIMIT environment variable
  • Implemented in internal/excel/pagination.go

Read the full file on GitHub · 123 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. 1mo ago First seen · 123 lines · 827 tokens per session scan A 24ac5befa5f7

Subscribe to this mod's changes

excel-mcp-server CLAUDE.md is an instructions file published in the GitHub repository Samcil/excel-mcp-server (0 stars, last pushed 2mo ago), licensed MIT. It adds 827 tokens to every session, about $0.0033 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 97% identical to excel-mcp-server CLAUDE.md, differing in 20 lines, and is treated as a copy.

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