Track AI Costs

Capture AI tool spending data and integrate it into your health snapshots and model routing decisions.

Prerequisites

  • A MODEL_ROUTING.md file (run /harness-init or copy from templates/MODEL_ROUTING.md if you don’t have one)
  • Access to your AI provider’s billing dashboard

1. Run the cost capture command 

/cost-capture

The command guides you through checking your provider dashboards and recording the data. It asks for:

  • Which providers you use (Anthropic, OpenAI, others)
  • Monthly spend for the reporting period
  • Token usage by model (if available)
  • Project share estimate (if multiple projects on one account)

2. Check your provider dashboard

The command gives you the URL for each provider:

  • Anthropic: https://console.anthropic.com/settings/billing
  • OpenAI: https://platform.openai.com/usage

Look for monthly spend, token usage breakdown, and any model-level detail. Read the numbers to the command when prompted.

3. Review the comparison

If you have a previous cost snapshot, the command computes:

  • Spend change (dollar amount and percentage)
  • Token volume change
  • Model mix shifts
  • Whether you’re within budget

If this is your first capture, there’s nothing to compare yet — the next quarterly capture will show the trend.

4. Set a budget (optional)

The command asks whether you have a monthly AI budget. If not, it offers to suggest one based on current spend. A budget turns cost tracking from observation into a guardrail — the health snapshot will flag when spend exceeds it.

5. Review MODEL_ROUTING.md updates

If the cost data suggests routing changes — for example, heavy frontier model use on tasks that could use standard models — the command proposes updates to MODEL_ROUTING.md. Each change is presented for your approval before being applied.

6. Find the output

The cost snapshot is saved to:

observability/costs/YYYY-MM-DD-costs.md

The next /harness-health run reads this file and populates the Cost Indicators section of the health snapshot.

7. Keep it current

Run /cost-capture quarterly, aligned with /assess:

  1. Run /assess (quarterly)
  2. Run /cost-capture (same session)
  3. Run /harness-health (reads both)

Over time, the cost snapshots build a spending trend that informs model routing decisions and budget conversations.