100M Tokens Tracked: 99.4% Were Input and Parallel Agents Make It Worse

Fazm Team··2 min read

100M Tokens Tracked: 99.4% Were Input and Parallel Agents Make It Worse

After tracking 100 million tokens across parallel Claude Code sessions, the numbers tell a clear story: 99.4% of all tokens were input. The model is reading far more than it is writing. And running 5 agents in parallel makes the problem five times worse.

The Input Token Problem

Every time a Claude Code agent starts a task, it reads your CLAUDE.md, scans relevant files, and builds context. That is all input tokens. The actual code it writes - the output - is a tiny fraction of the total.

With a single agent, this is manageable. With 5 parallel agents, each one is independently reading the same project context. Five agents reading the same CLAUDE.md, the same project structure, the same reference files. Your API bill becomes a second SaaS subscription.

The Numbers

At typical API pricing, 100M tokens is not cheap. When 99.4% of that is input, the cost optimization lever is obvious: reduce what each agent needs to read, not what it writes.

The math is simple. If you can cut each agent's input context by 40%, you save 40% on 99.4% of your total token usage. That is a meaningful reduction in your monthly bill.

How CLAUDE.md Scoping Helps

Aggressive scoping in CLAUDE.md is the highest-leverage cost optimization:

  • Per-folder scope files so each agent only reads context relevant to its task
  • Explicit file boundaries so agents do not scan the entire codebase for context
  • Concise specs that convey the same information in fewer tokens
  • Caching-friendly patterns that let the API cache repeated context across sessions

The goal is not to give each agent less information - it is to give each agent only the information it needs.

The Real Cost of Parallel Agents

Parallel agents are worth the cost when they save you time. But you should know what you are paying. Track your token usage, break it down by input vs output, and optimize the input side. That is where 99.4% of your money goes.

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Fazm is an open source macOS AI agent. Open source on GitHub.

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