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.
npx skills add gaia-research/gaia-skill-heaven --skill cost-measurementgit clone --depth 1 https://github.com/gaia-research/gaia-skill-heavenWrote 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.
[](https://agentmods.dev/skills/gaia-research/gaia-skill-heaven/cost-measurement)<a href="https://agentmods.dev/skills/gaia-research/gaia-skill-heaven/cost-measurement"><img src="https://agentmods.dev/badge/skills/gaia-research/gaia-skill-heaven/cost-measurement/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.
<a href="https://agentmods.dev/skills/gaia-research/gaia-skill-heaven/cost-measurement"><img src="https://agentmods.dev/badge/skills/gaia-research/gaia-skill-heaven/cost-measurement.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00062 | $0.01171 |
| Opus 5.5 | $0.00025 | $0.00468 |
| Sonnet 5.5 | $0.00012 | $0.00234 |
| Haiku 4.5 | $0.00006 | $0.00117 |
Grade A, and why
cost-measurement 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Cost Measurement
gaia-research/skill-cost is the canonical basis for every cost measure in the Gaia
ecosystem. Do not hand-roll token accounting, do not read harness JSONL yourself, and do not
quote a price from memory. If a number is going into a report, it comes from here.
Repo: https://github.com/gaia-research/skill-cost · registry id gaia-research/skill-cost
Why this and not self-reported numbers
skill-cost reads the session logs the harness actually wrote and prices every turn against
BerriAI/litellm's canonical
model_prices_and_context_window.json, refreshed weekly. That means:
- Numbers are persisted usage, not a model's guess about its own consumption.
- Cache reads and cache writes are counted separately — which matters enormously, since cache reads routinely dominate total tokens and are priced very differently.
- Every harness is priced the same way, so cross-harness arms are comparable.
Asking a model how many tokens it used produces confabulation. Reading the log does not.
Supported harnesses
| Harness | Session storage |
|---|---|
| pi | ~/.pi/agent/sessions/**/*.jsonl |
| Claude Code | ~/.claude/projects/**/*.jsonl |
| OpenAI Codex | ~/.codex/sessions/**/*.jsonl |
| opencode | ~/.local/share/opencode/**/*.jsonl |
| Hermes Agent | $HERMES_HOME/state.db (SQLite, read-only; usage tables only, never transcripts) |
Known gap: Grok is not supported. If a Grok arm needs pricing, that is a
parse_grok function in cost.py — adding a line-oriented harness is one small parser. The
repo is part of our ecosystem and may be extended when a gap blocks a measurement.
Run
cd ~/skill-cost
python3 cost.py # newest logical session across all harnesses
python3 cost.py --latest # latest session per harness in cwd
python3 cost.py --today --by-model # today, per-model breakdown
python3 cost.py --all --list # one line per session, everything
python3 cost.py --since 2026-08-01 --harness claude-code
python3 cost.py --cwd "$PWD" # only sessions rooted at this directory
python3 cost.py --session 019f4e66 # substring match on session id
python3 cost.py --json # machine-readable
python3 cost.py --offline # no network; use bundled prices.json
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.
- 1mo ago First seen · 121 lines · 62 tokens per session scan A 9beb1f360772
cost-measurement is a skill published in the GitHub repository gaia-research/gaia-skill-heaven (4 stars, last pushed today), licensed MIT. It adds 62 tokens to every session and 1,171 once invoked, about $0.0002 per session on Opus 5.5. 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.
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