Re Kaitai

MCP server exposing Kaitai Struct for custom binary format reverse engineering.

Tools

Tool	What it does
check_compiler	Confirm kaitai-struct-compiler is installed
list_known_formats	List bundled .ksy formats
download_format	Download a .ksy from the kaitai-formats gallery
compile_format	Compile .ksy → Python at runtime
parse_with_format	Parse a binary with a compiled or precompiled format
visualize	Same as parse_with_format, named for the intent
diff_parses	Parse two files and return a structural diff

Install

# System dependency
brew install kaitai-struct-compiler   # macOS
scoop install kaitai-struct-compiler  # Windows
# Linux: download prebuilt from https://github.com/kaitai-io/kaitai_struct_compiler/releases

# Python
pip install kaitaistruct
pip install -e ./servers/re-kaitai

Usage pattern (in Claude Code)

1. "Decode this firmware blob"
2. Claude identifies the file magic (e.g. LZMA header)
3. Claude downloads the matching .ksy: download_format("lzma")
4. Claude compiles: compile_format("/path/lzma.ksy")
5. Claude parses: parse_with_format(path="/path/blob", ksy_path="/path/lzma.ksy")
6. Claude inspects the parse tree, iterates on the .ksy, re-parses

The Kaitai workflow is iterative: compile → parse → fix the schema → re-compile → parse again.