Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/DaizeDong/buy-me-a-carnpx agentmods add skills/daizedong/buy-me-a-car/otd-calculatorWrote 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/daizedong/buy-me-a-car/otd-calculator)<a href="https://agentmods.dev/skills/daizedong/buy-me-a-car/otd-calculator"><img src="https://agentmods.dev/badge/skills/daizedong/buy-me-a-car/otd-calculator/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/daizedong/buy-me-a-car/otd-calculator"><img src="https://agentmods.dev/badge/skills/daizedong/buy-me-a-car/otd-calculator.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 | $0.00122 | $0.02137 |
| Opus 5 | $0.00061 | $0.01069 |
| Sonnet 5 | $0.00024 | $0.00427 |
| Haiku 4.5 | $0.00012 | $0.00214 |
Grade A, and why
otd-calculator 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 — 154 lines — stays where its author put it; the contents beside it link to each section on GitHub.
OTD Calculator
Caveat: this skill is one author's playbook + 5-scenario stress test. Verify state fees / CPO terms / EV credits / dealer practices against current sources before quoting numbers to a dealer or making financial decisions. Not tax, legal, or financial advice. last_verified: 2026-05-18 Scope: narrow OTD math only. For full negotiation flow see
../orchestrator/SKILL.md. For state fee data see../state-fee-lookup/SKILL.md.
Core formula (forward: Sale -> OTD)
Taxable = Sale + Doc (in most states; CA is a notable exception, see gotchas)
Tax = Taxable * (StateRate + LocalRate)
OTD = Sale + Doc + Tax + Title + Reg + Other
Other covers tire/battery/environmental fees, EV reg surcharge, lien recording, and any add-ons that survived F&I. Should be a short itemized list, not a black box.
Reverse formula (target OTD -> Sale ceiling)
Given a target OTD you will pay, solve for the maximum Sale price you can accept:
Sale = (TargetOTD - Doc * (1 + Rate) - Title - Reg - Other) / (1 + Rate)
Where Rate = StateRate + LocalRate. Doc is taxed in most states, hence the (1 + Rate) factor on Doc inside the bracket. Verify per-state in the state-fee-lookup skill.
Trade-in case
In states granting trade-in tax credit (most; CA, KY, DC do NOT), trade value reduces the taxable base:
Taxable = (Sale + Doc - Trade)
Forward with trade:
OTD = Sale + Doc + (Sale + Doc - Trade) * Rate + Title + Reg + Other
Reverse with trade (solve for Sale given target OTD):
Sale = (TargetOTD + Trade*Rate - Doc*(1+Rate) - Title - Reg - Other) / (1+Rate)
If state does NOT grant credit, drop the Trade term from the taxable base.
State quick rates (15 most-common)
| State | Combined typical | Doc cap | Title | Reg (1yr) | Trade credit |
|---|---|---|---|---|---|
| NJ | 6.625% | $799 | $85 | $70 | Yes |
| NY | 8.875% (NYC) / 8% (most) | $175 | $50 | $100 | Yes |
| PA | 6% (8% Philly, 7% Allegheny) | none | $58 | $45 | Yes |
| CT | 6.35% (7.75% >$50k) | none | $25 | $80 | Yes |
| MA | 6.25% | none | $75 | $60 | Yes |
| CA | 8.75-9.5% (combined) | $85 | $25 | ~1%/yr MSRP | NO |
| TX | 6.25% (no local) | $225 | $33 | $50 + $200 EV | Yes |
| FL | 6-7.5% (combined) | none | $77 | $225 | Yes |
| IL | 7.5-10.25% (combined) | $347 | $155 | $151 | Yes |
| OH | 6-7.5% (combined) | $250 | $15 | $31 | Yes |
| MI | 6% | $230 | $15 | $100 | Yes capped 9k (2025) |
| GA | 6.6% TAVT one-time | none | $18 | $20 | Yes (on TAVT) |
| WA | 8-10% (combined) | $200 | $15 | $80 | Yes |
| MD | 6% | $800 | $100 | $135 | Yes |
| VA | 4.15% min $75 | $599 | $15 | $41 | NO |
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 · 154 lines · 122 tokens per session scan A cc1cb24c5b39
otd-calculator is a skill published in the GitHub repository DaizeDong/buy-me-a-car (5 stars, last pushed 8d ago), licensed MIT. It adds 122 tokens to every session and 2,137 once invoked, about $0.0006 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.
Other skills, from other repositories
chief-financial-officer
Owns the financial position: planning, budgeting, forecasting, unit economics, cash, and the numbers the business is run and reported on. Use this to build or challenge a budget, model a decision's financial consequence, assess unit economics or runway, evaluate an investment or spend request, set financial controls…
fundraising-and-investor-relations
Raises capital and manages the relationship afterward — deciding how much and why, understanding what dilution and preferences actually cost, running a process with real competitive tension, preparing for diligence before it starts, and reporting to investors and a board in a way that keeps support when results are…
cost-accounting
Establishes what something actually costs — fixed, variable and mixed cost behavior, absorption versus variable costing, job-order, process and activity-based methods, breakeven and operating leverage, and price/volume/mix decomposition. Use this to set a price floor, explain why revenue or margin moved, decide make…
financial-statement-analysis
Reads a set of financial statements and establishes what changed and why — fluctuation analysis against prior period and against budget, profitability, liquidity, solvency and efficiency ratios, benchmarking, and the non-GAAP measures presented alongside them. Use this to interpret results, review a counterparty's or…
internal-controls-and-audit
Designs and tests controls over financial reporting — segregation of duties, approval limits, evidence, and preparing for audit. Use this to design controls for a process, prepare for an external audit, respond to an audit finding, set approval thresholds, or assess where a small team's segregation of duties is…
payroll-operations
Runs the pay cycle so it is right, on time, and provable — the calendar and cutoffs, what feeds pay from the HRIS and time systems, gross-to-net and the deductions in it, multi-jurisdiction registration and tax filing, off-cycle payments and corrections, and the reconciliation to the general ledger. Use this to design…