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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 negokaz/excel-mcp-server. It costs 827 tokens per session, scanned A, original, MIT.

Project instructions for an MCP server that connects AI assistants to Microsoft Excel files. MCP is a standard way for an AI assistant to call external tools.

In plain words
What is it for?
Use them when developing or maintaining this Excel integration, running its tests, checking code quality, or investigating its architecture.
Why use it?
They explain how to build, test, format, and debug the server, including its Windows live-Excel and cross-platform file-operation backends.

Instructions file for Claude Code

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

This is negokaz/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 1.0k +4 1y ago A scan 827 tokens original MIT
View the source file negokaz/excel-mcp-server
Reuse

Borrowing it

Nothing to install: this file belongs to negokaz/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/negokaz/excel-mcp-server/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/negokaz/excel-mcp-server

Made for: Claude Code.

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README.md
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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. 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 5.1 $0.00827 $0.00827
Opus 5 $0.00413 $0.00413
Sonnet 5 $0.00165 $0.00165
Haiku 4.5 $0.00083 $0.00083

Measured 6d ago against content hash a6e1817687b8, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, 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 6d 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

Copies of this mod

1 near-identical copy found in the catalogue:

CLAUDE.md · 109 lines

How it starts

The opening of the file, as written. The whole thing — 109 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/excel-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 · 109 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. 6d ago First seen · 109 lines · 827 tokens per session scan A a6e1817687b8

Subscribe to this mod's changes

excel-mcp-server CLAUDE.md is an instructions file published in the GitHub repository negokaz/excel-mcp-server (1,021 stars, last pushed 1y ago), licensed MIT. It adds 827 tokens to every session, about $0.0041 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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