cost-gate

Claude Code hook that tracks cumulative token spend across a session and blocks tool calls when a budget ceiling is hit.

Install

npm install -g cost-gate

Setup

Add to ~/.claude/settings.json as both PreToolUse and PostToolUse hooks with matcher ".*".

Configuration

Create .cost-gate.json in your project root (optional):

{
  "budget": 10.00,
  "costPerToken": 0.000003,
  "warningThreshold": 0.8
}

How It Works

1. Every tool call input is estimated as tokens (payload size / 4)
2. Every tool response is estimated as tokens (PostToolUse, advisory)
3. Running total stored in .cost-gate-session.json
4. When total exceeds budget: all tool calls denied
5. At warning threshold (80%): allowed but warning injected

CLI

cost-gate status    # show current session spend
cost-gate reset     # clear session, start fresh

Requirements

• Node.js >= 22
• ESM only

License

MIT