The MCP server token tax is the context budget every tool definition eats before your agent does a single useful thing. To measure it, pull the server's tools/list JSON and tokenize each definition. Claude Code's Tool Search defers loading — it doesn't reduce the tax. Run the 60-second audit below and you'll see your real per-tool cost instead of repeating someone else's number.
In short: the MCP server token tax is the context budget every tool definition eats before your agent does anything. To measure it, pull the server's tools/list and tokenize each definition with tiktoken. My run of the real filesystem server: 14 tools, 2,638 tokens, ~1.3% of a 200K window.
AI disclosure: I wrote mcp_token_tax.py with AI assistance and ran it myself before publishing. Every number below is pasted from a real run of that script, or it's an external figure with a dated link next to it. I label which is which.
You've seen the figure quoted everywhere this spring: "the GitHub MCP server costs you tens of thousands of tokens before you ask anything." It gets repeated in threads, in newsletters, in conference hallway chatter. Here's a question almost nobody answers when they quote it: with which tokenizer, against which tools/list?
