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io.github.mdfifty50-boop/token-lens

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Context window token analysis and budget management

Source code Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

NPM package token-lens-mcp
Claude Code 
claude mcp add token-lens -- npx -y token-lens-mcp@0.1.2
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "token-lens": {
            "command": "npx",
            "args": [
                "-y",
                "token-lens-mcp@0.1.2"
            ]
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. token-lens-mcp
  2. Install
  3. Tools
  4. Resources
  5. Development
  6. License

token-lens-mcp

MCP server for analyzing and optimizing context window token usage. MCP tool definitions consume 40-72% of context windows before any user work begins — this server helps you measure, compress, and eliminate that waste.

Install

npx token-lens-mcp
Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "token-lens": {
      "command": "npx",
      "args": ["token-lens-mcp"]
    }
  }
}
Claude Code
claude mcp add token-lens -- npx token-lens-mcp

Tools

audit_context_budget

Analyze the token cost of your MCP tool definitions. Estimates tokens per tool using chars/4 approximation on the full JSON definition.

Params:

  • tools — Array of {name, description, schema} objects

Returns: Per-tool token cost (sorted by cost), total tokens, percentage of 128K/200K/1M context windows.

optimize_tool_loading

Given a task description, recommend the minimal set of tools needed. Uses keyword matching and category relevance scoring.

Params:

  • task_description — What you're trying to accomplish
  • available_tools — Array of {name, description, category?}

Returns: Recommended tools sorted by relevance, excluded tools, estimated tokens saved.

compress_schema

Compress verbose tool schemas to reduce token usage.

Params:

  • tool_name — Name of the tool
  • schema — JSON Schema object to compress
  • level — "light" | "medium" | "aggressive"

Levels:

  • light — Remove descriptions under 20 chars
  • medium — Shorten descriptions to 50 chars, remove examples
  • aggressive — Strip all descriptions, keep only types and required fields

Returns: Compressed schema, original/compressed token counts, savings percentage.

analyze_session_usage

Track which tools are actually called vs loaded during a session.

Params:

  • session_id — Unique session identifier
  • action — "register_tool" | "log_call" | "report"
  • tool_name — Tool name (required for register_tool/log_call)
  • tool_tokens — Token cost (for register_tool, default 50)

Report returns: Loaded vs used counts, waste percentage, unused tools ranked by token cost.

suggest_removals

Identify tools that can be safely removed based on usage patterns.

Params:

  • usage_history — Array of {tool_name, call_count, last_used_days_ago}

Scoring: never_used (priority 3) > not_used_30_days (priority 2) > rarely_used (priority 1)

Returns: Removal candidates with reasons and estimated token savings.

get_optimization_report

Full context window health check combining audit, removal suggestions, and compression recommendations.

Params:

  • tools — Array of tool definitions
  • usage_history — Optional usage history array

Returns: Executive summary with health grade (excellent/good/fair/poor), audit results, removal suggestions, compression opportunities, and actionable recommendations.

Resources

token-lens://tips

Best practices guide for reducing MCP context window bloat, including schema design tips, token budget guidelines, and dynamic tool loading strategies.

Development

npm install
npm test
npm run dev  # watch mode

License

MIT

Frequently asked questions

What is io.github.mdfifty50-boop/token-lens?

Context window token analysis and budget management

How do I install io.github.mdfifty50-boop/token-lens?

It runs on your machine. In Claude Code: claude mcp add token-lens -- npx -y token-lens-mcp@0.1.2. For other clients, paste the JSON configuration from this page into their MCP settings.

Does io.github.mdfifty50-boop/token-lens need an API key?

Its registry entry lists no required key or secret. Some features may still need an account with the service it connects to.

Is io.github.mdfifty50-boop/token-lens open source?

Its code is public on GitHub, but the repository does not declare a standard license.

Who maintains io.github.mdfifty50-boop/token-lens?

It is published by mdfifty50-boop. AI.tn lists it but does not maintain or endorse it.

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