Crate mcp_rtk 

mcp-rtk

A token-optimizing MCP proxy that sits between Claude and any upstream MCP server, compressing tool responses to reduce token consumption by 60–90%.

Architecture

Claude ←(stdio)→ mcp-rtk ←(stdio/subprocess)→ upstream MCP server

mcp-rtk is both an MCP server (for Claude) and an MCP client (for upstream). It forwards list_tools and call_tool requests, applying JSON compression filters on responses before returning them.

Modules

• config — TOML configuration loading with per-tool filter rules and external preset auto-discovery from ~/.local/share/mcp-rtk/presets/.
• filter — The 8-stage filter pipeline and generic JSON compression functions.
• hot_reload — File watcher that hot-reloads external presets and atomically rebuilds the filter engine via arc_swap::ArcSwap.
• proxy — ProxyServer and ProxyClient implementing the MCP server/client handlers.
• tracking — SQLite-backed token savings metrics.

Modules

config

Configuration loading with preset auto-detection.

diff

Side-by-side diff display for raw vs filtered tool responses.

discover

Analyze Claude Code session logs to find MCP servers that would benefit from mcp-rtk filtering.

display

Shared ANSI display utilities used by tracking and discover.

filter

The 8-stage filter pipeline and generic JSON compression functions.

hot_reload

Hot reload support for external presets.

install

Install and uninstall mcp-rtk wrapping in MCP JSON config files.

preset_ops

Preset operations: interactive init and remote pull.

proxy

MCP proxy server and client handlers.

tracking

SQLite-backed token savings metrics.