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 jeffreytse/grimoire-core --skill calculate-total-cost-of-ownershipgit clone --depth 1 https://github.com/jeffreytse/grimoire-coreWrote 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/jeffreytse/grimoire-core/calculate-total-cost-of-ownership)<a href="https://agentmods.dev/skills/jeffreytse/grimoire-core/calculate-total-cost-of-ownership"><img src="https://agentmods.dev/badge/skills/jeffreytse/grimoire-core/calculate-total-cost-of-ownership/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/jeffreytse/grimoire-core/calculate-total-cost-of-ownership"><img src="https://agentmods.dev/badge/skills/jeffreytse/grimoire-core/calculate-total-cost-of-ownership.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 | $0.00029 | $0.01293 |
| Opus 5 | $0.00015 | $0.00647 |
| Sonnet 5 | $0.00006 | $0.00259 |
| Haiku 4.5 | $0.00003 | $0.00129 |
Grade A, and why
calculate-total-cost-of-ownership 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 12d 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 — 60 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Calculate Total Cost of Ownership
Compute the full 5-year cost of owning a vehicle — including depreciation, financing, fuel, insurance, maintenance, and taxes — to make financially sound vehicle comparisons.
Why This Is Best Practice
Adopted by: AAA (publishes annual driving cost benchmarks), Edmunds (TCO used by 10M+ buyers/year), Consumer Reports, U.S. General Services Administration fleet procurement, corporate fleet managers
Impact: TCO analysis reveals that vehicles with $5,000–$15,000 lower sticker price can cost $8,000–$22,000 more over 5 years due to depreciation and fuel; AAA reports average TCO of $10,728/year for a new midsize sedan (2023) — 40% higher than most buyers estimate
Why best: Sticker price represents only 30–40% of total ownership cost; depreciation alone accounts for 35–50% of 5-year TCO and is invisible without systematic calculation
Sources: AAA "Your Driving Costs 2023"; Edmunds "True Cost to Own" methodology white paper; Consumer Reports "Car Ownership Cost Guide" (2023)
Steps
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Define the comparison scope — Specify vehicle(s) being compared, ownership duration (standard: 5 years / 75,000 miles), annual mileage estimate, ZIP code (affects insurance and fuel price), and financing vs. cash purchase.
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Calculate depreciation — Look up residual value at 5 years using Edmunds or Black Book; depreciation = purchase price minus 5-year resale value. Rule of thumb: most mass-market vehicles lose 50–60% of value in 5 years; luxury vehicles 60–70%; trucks/SUVs with high demand 35–50%.
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Calculate financing cost — Total interest paid = (monthly payment × number of payments) minus principal. Use a loan amortization calculator; enter purchase price minus down payment, interest rate (check current rates at credit unions, banks, and dealer), and loan term (36–72 months). Longer terms = more total interest despite lower payments.
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Calculate insurance cost — Get actual quotes for each vehicle being compared (same coverage levels); annual premium × 5 years. Insurance varies 40–200% between vehicle models on identical driver profiles — sports cars, German luxury, and high-theft vehicles cost significantly more.
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.
- 12d ago First seen · 60 lines · 29 tokens per session scan A 5e8bc4ae316d
calculate-total-cost-of-ownership is a skill published in the GitHub repository jeffreytse/grimoire-core (4 stars, last pushed 24d ago), licensed MIT. It adds 29 tokens to every session and 1,293 once invoked, about $0.0001 per session on Opus 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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