notab

MCP server and CLI tool for normalizing whitespace — convert tabs to spaces or spaces to tabs.

Install

go build -o notab && codesign -s - notab
cp notab /usr/local/bin/

Usage

MCP Server

Default mode — communicates over stdin/stdout using JSON-RPC (MCP protocol).

notab

Add to Claude Code:

claude mcp add --transport stdio notab -- notab

Tool: notab

Parameter	Type	Required	Default	Description
file	string	yes		Absolute path to the file to normalize
spaces	integer	no	4	Number of spaces per tab
tabs	boolean	no	false	Inverse mode: convert leading spaces to tabs

CLI

# Tabs to spaces (default)
notab --cli --file /path/to/file.go

# Custom spacing
notab --cli --file /path/to/file.py --spaces 2

# Spaces to tabs (for Makefiles, etc.)
notab --cli --file /path/to/Makefile --tabs

Exit codes

Code	Meaning
0	Success
1	Error
2	No changes

Output

JSON with normalization results:

{
  "file": "/path/to/file.go",
  "replacements": 12,
  "lines_affected": 5,
  "direction": "tabs_to_spaces"
}

How it works

• Tabs to spaces (default): Replaces all tab characters with the configured number of spaces.
• Spaces to tabs (--tabs / tabs: true): Replaces leading space groups with tabs. Only converts complete groups at the start of lines — inline spaces are preserved.

File permissions are preserved during writes.

License

MIT