MCP Lens is a zero-dependency transparent stdio/SSE proxy, real-time JSON-RPC 2.0 traffic sniffer, BPE token weight auditor, and visual playground for AI agent developers using the Model Context Protocol.

How does MCP Lens reduce AI context token costs?

MCP Lens analyzes tool schemas and strips redundant descriptions, verbose examples, and parameter bloat while preserving exact JSON typing and required fields, reducing context token overhead by 30% to 45% per agent turn.

Does MCP Lens require external pip or npm packages?

No. MCP Lens is engineered strictly with 100% Python 3.10+ standard library modules and vanilla ES6 browser JavaScript, with zero external dependencies.

MCP Lens — Zero-Dependency Model Context Protocol Traffic Sniffer & Token Weight Auditor

Interactive Tool Runner

Dispatch live simulated JSON-RPC calls

SANDBOX

Select Discovered MCP Tool:

Input Schema Arguments:

Execution Output:

Click "Run Tool" to dispatch a JSON-RPC 2.0 tools/call frame.

Schema Token Minifier

Side-by-side AST comparison and token savings

Raw: 0 tk Min: 0 tk -0%

Original MCP Schema Unoptimized

Minified Schema Production Ready

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Pro Production Schema Locked

Unlock 35%+ token savings, batch schema minification, and instant Cursor & Claude rules export.

⚡ Stripe $19

MCP Tool Token Weight Leaderboard

Detailed breakdown of parameter bloat and financial cost per 1M tool calls

Tool Name	Description Snippet	Raw Tokens	Minified Tokens	Tokens Saved	Est. Cost Saved / 1M

Continuous In-Memory AST Minifier Daemon & Token Caching Layer

Auto-injects minified schemas on the fly into Claude Code, Cursor, and Antigravity stdio pipes without altering server code.

[DAEMON] Intercepting tools/list response...
[AST] Stripped 1,420 tokens from sqlite_query_records and github_pr_diff.
[CACHE] Saved 45,210 tokens across 32 agent iterations today.
[PROXY] Forwarding pristine frame to agent client...

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Unlock Autonomous AST Proxy Minification

Automatically intercept and minify all outgoing MCP tool schemas in real-time. Never burn unnecessary tokens on agent runs again.

Stdio Proxy Integration Recipes

1-line drops to wrap MCP servers in Claude Code, Cursor, Windsurf, or Antigravity

Claude Code (CLI)

claude mcp add my-tool -- mcp-lens -- python /path/to/server.py

Cursor (settings.json)

{
  "mcpServers": {
    "proxied-tool": {
      "command": "mcp-lens",
      "args": ["--", "node", "/path/to/server.js"]
    }
  }
}

Antigravity / Windsurf Stdio Command

mcp-lens proxy --port 8109 -- npx -y @modelcontextprotocol/server-filesystem /tmp

Inspect, Audit & Minify MCP Stdio Traffic in Real-Time

Interactive Tool Runner

Schema Token Minifier

Pro Production Schema Locked

MCP Tool Token Weight Leaderboard

Unlock Autonomous AST Proxy Minification

Stdio Proxy Integration Recipes

JSON-RPC 2.0 Frame Inspector

Unlock MCP Lens Pro

Inspect, Audit & Minify
MCP Stdio Traffic in Real-Time