A local MCP server that analyses how much text and instruction space an AI agent is using. A context window is the amount of information an agent can consider at once.

Use it to inspect context-window usage and manage token limits during agent work.

It helps track context usage and manage the available token budget, where tokens are the small text units used by language models.

token-lens — MCP server for Claude Code and Codex by mdfifty50-boop

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo

git clone --depth 1 https://github.com/mdfifty50-boop/token-lens-mcp

Made for: Claude Code, Codex, Cursor, Gemini CLI, OpenCode.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/mcp/mdfifty50-boop/token-lens-mcp/token-lens/github.svg)](https://agentmods.dev/mcp/mdfifty50-boop/token-lens-mcp/token-lens)

Your own site

<a href="https://agentmods.dev/mcp/mdfifty50-boop/token-lens-mcp/token-lens"><img src="https://agentmods.dev/badge/mcp/mdfifty50-boop/token-lens-mcp/token-lens/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/mcp/mdfifty50-boop/token-lens-mcp/token-lens"><img src="https://agentmods.dev/badge/mcp/mdfifty50-boop/token-lens-mcp/token-lens.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session not measured What this adds to a session before it is invoked.

When invoked not measured Not applicable: nothing here is loaded into a session.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin unknown No closer match found in the catalogue.

Security

Grade A, and why

token-lens scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

server.json · 10 lines

The source is not reproduced here

No licence file

Read it on GitHub

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

10d ago First seen · 10 lines scan A ebc56998ef85

Subscribe to this mod's changes

token-lens is an MCP server published in the GitHub repository mdfifty50-boop/token-lens-mcp (0 stars, last pushed 4mo ago), with no licence file. Its token cost is not measured: an MCP server costs its tool schemas, not its config file. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Memory and context ai-agents context-window llm-tools mcp mcp-server model-context-protocol

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token-lens