mcp-wallfacer 0.4.3

Runtime fuzzing and invariant-testing harness for MCP servers.

mcp-wallfacer (pip wrapper)

Thin Python wrapper around the mcp-wallfacer Rust binary. On first invocation, downloads the matching platform binary from the GitHub release into a per-user cache and execs it.

pip install mcp-wallfacer
wallfacer --help

What it installs

The Python package is tiny — pure-stdlib launcher, no extra deps. The actual wallfacer binary is downloaded on the first run from the matching GitHub release.

Platform	Architecture
Linux	x86_64, aarch64
macOS	x86_64 (Intel), aarch64 (Apple silicon)
Windows	x86_64

For other platforms, build from source:

cargo install mcp-wallfacer

Environment variables

Var	Default	Purpose
WALLFACER_VERSION	v<package version>	Pin the GH release to download.
WALLFACER_CACHE_DIR	platform default	Override the binary cache location.

Default cache locations:

• Linux: $XDG_CACHE_HOME/mcp-wallfacer (or ~/.cache/mcp-wallfacer)
• macOS: ~/Library/Caches/mcp-wallfacer
• Windows: %LOCALAPPDATA%\mcp-wallfacer

How the wrapper works

1. wallfacer is registered as a console script via [project.scripts] in pyproject.toml. It maps to wallfacer_cli.main.
2. On invocation, main() checks the cache for a binary matching the current platform + version. If absent, it downloads + extracts the GitHub release tarball.
3. subprocess.run forwards argv and stdio to the binary, exit code propagates back.

The wrapper executes no Python at runtime beyond the launcher itself, so behaviour is identical to a direct cargo install of the same version.