MCP RTK：削减 90% 的 MCP 服务器 token

I use Claude Code every day for development. Like many developers, I've connected several MCP servers (GitLab, Grafana, Sentry...) to give Claude direct access to my tools. The problem: every MCP call injects tens of thousands of tokens into the context, and the bill spirals fast. I built MCP RTK to fix this. It's an MCP proxy written in Rust that sits between Claude Code and MCP servers, filtering responses before they reach the model. Result: over 267 million tokens saved across my 38,000+ commands. The problem: oversized MCP responses The MCP protocol (Model Context Protocol) lets Claude interact with external tools. When Claude calls an MCP tool, the server returns a JSON response. The issue is that these responses often contain: empty or null fields that add nothing technical metadata (internal timestamps, pagination IDs, HTTP headers) very long values (full logs, HTML descriptions, entire diffs) arrays with dozens of entries when 5 would suffice A single list_issues call on GitLab can consume over 180,000 tokens. Claude only needs a fraction to answer the question. The rest is pure waste. Over a typical work session with 50 to 100 MCP calls, that easily adds up to 500,000 wasted tokens injected into the context. The solution: an 8-step filtering proxy MCP RTK sits transparently between Claude Code and MCP servers. No workflow change needed: Claude keeps calling the same tools, but responses pass through a filtering pipeline before reaching the context. The pipeline has 8 steps: Remove null and empty fields - fields without values are stripped Truncate long strings - values exceeding a configurable threshold are cut Field whitelist - only useful fields are kept Field blacklist - known useless fields are removed Deduplication - identical entries are merged Array compression - long arrays are sampled Technical metadata removal - API-internal fields are stripped Normalization - output format is standardized Each step is independently configurable. You can enable or disable each filter, adjust thresholds, and define server-specific rules. Configuration with presets Configuration uses a TOML file. MCP RTK ships with community presets for popular servers: [servers.gitlab] preset = "gitlab" [servers.grafana] preset = "grafana" [servers.sentry] preset = "sentry" Enter fullscreen mode Exit fullscreen mode Each preset defines which fields to keep, which to exclude, and appropriate truncation thresholds for the server. For custom servers, you define rules directly: [servers.my-api] whitelist = ["id", "name", "status", "created_at"] max_string_length = 500 max_array_length = 10 Enter fullscreen mode Exit fullscreen mode MCP RTK auto-detects installed MCP servers and offers to configure them. Results Across my 38,000+ commands, MCP RTK has saved 267 million tokens with an average reduction rate of 87%. On Opus 4.6 ($15/M input tokens), that's roughly $4,000 in savings: Useful information is preserved. Claude responds with the same accuracy, but consumes far fewer tokens per session. The mcp-rtk gain command lets you track savings in real time: Tokens saved: 267.1M (86.7%) Efficiency meter: █████████████████████░░░ 86.7% Enter fullscreen mode Exit fullscreen mode Installation MCP RTK is distributed as a single binary: cargo install mcp-rtk Enter fullscreen mode Exit fullscreen mode One line change in your Claude Code config - wrap the existing MCP command with mcp-rtk --: { "mcpServers": { "gitlab": { "command": "mcp-rtk", "args": ["--", "npx", "-y", "@nicepkg/gitlab-mcp"], "env": { "GITLAB_PERSONAL_ACCESS_TOKEN": "glpat-..." } } } } Enter fullscreen mode Exit fullscreen mode MCP RTK detects the upstream server from the command and loads the matching preset automatically. Why Rust? Rust was a deliberate choice. The proxy must process every MCP response with minimal latency to avoid slowing down the workflow. Rust provides: near-instant startup (no JVM, no runtime) minimal memory footprint (a few MB) a single binary with no dependencies to install compile-time memory safety guarantees The code is open source MCP RTK is published under the MIT license on GitLab (mirror on GitHub). Community presets are maintained by users: anyone can contribute their own configurations for new MCP servers. The project is part of a tooling ecosystem I'm building around Claude Code, alongside Skill Radar (detecting repetitive patterns in sessions) and Claude Deck (multi-workspace for parallel sessions). To learn how to write your own skills, see the guide on effective skills. The project page has installation links and documentation.