# DecisionsCalc MCP server

Calculators built on **official rules**, for AI agents. Free, no key, read-only.

- **Endpoint:** `https://decisionscalc.com/mcp` (Model Context Protocol, Streamable HTTP, JSON responses)
- **Official MCP Registry:** `com.decisionscalc/calculators`
- **Docs for agents:** https://decisionscalc.com/for-agents/
- **Server card:** https://decisionscalc.com/.well-known/mcp/server-card.json

Every result includes the calculator page a person can open and the **official sources** (gov.ie, Revenue, Citizens
Information, GOV.UK, Canada.ca, Québec.ca, ATO, IRD…) it is based on, so an agent can cite them. Rates are dated and
re-checked when budgets change.

## Use it

```json
{ "mcpServers": { "decisionscalc": { "type": "http", "url": "https://decisionscalc.com/mcp" } } }
```

Example call:

```bash
curl -s https://decisionscalc.com/mcp -H 'Content-Type: application/json' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"ireland_rent_tax_credit","arguments":{"monthlyRent":1500}}}'
```

## Tools

| Tool | What it does | Calculator |
|---|---|---|
| `ireland_what_can_i_claim` | Ireland: list the social welfare payments and tax credits a household may get (Child Benefit, New Baby Grant, Working Family Payment, Maternity Benefit, Carer’s Allowance, State Pension, Fuel Allowance, Rent Tax Credit) with estimated amounts, using official 2026/2027 rates. | [page](https://decisionscalc.com/tools/ireland-what-can-i-claim/) |
| `ireland_working_family_payment` | Ireland: estimate the Working Family Payment (weekly, tax-free) for a family, from gross pay, number of children and hours worked, using the official income limits (2026, and +€30 from January 2027) and the 60% rule. | [page](https://decisionscalc.com/tools/ireland-working-family-payment-calculator/) |
| `ireland_rent_tax_credit` | Ireland: how much Rent Tax Credit a renter can claim for each year 2022–2026 (20% of rent, capped per year), including back-claims. Claims for 2022 must be made by 31 December 2026 (Revenue four-year rule). | [page](https://decisionscalc.com/tools/ireland-rent-tax-credit-calculator/) |
| `ireland_carers_allowance` | Ireland: estimate the weekly Carer’s Allowance from the official means test (income disregard €1,000/€2,000 from July 2026, €1,150/€2,300 from July 2027; savings bands; Department rate table). | [page](https://decisionscalc.com/tools/ireland-carers-allowance-calculator/) |
| `ireland_fuel_allowance` | Ireland: check the Fuel Allowance means test (66+: €534 a week single, €640.80 from January 2027; under 66 needs a qualifying payment) and the 2026/27 season amount (€38, then €43 a week; €1,134 in lump sums). | [page](https://decisionscalc.com/tools/ireland-fuel-allowance-calculator/) |
| `ireland_state_pension_contributory` | Ireland: estimate the State Pension (Contributory) weekly rate under the Department’s Total Contributions Approach (paid PRSI + up to 520 credits + HomeCaring Periods; 2,080 for the full rate). | [page](https://decisionscalc.com/tools/ireland-state-pension-calculator/) |
| `ireland_budget_2027_take_home` | Ireland: take-home pay in 2026 against 2027 after Budget 2027 (income tax bands and credits, USC, PRSI, rent credit), line by line. | [page](https://decisionscalc.com/tools/ireland-budget-2027-calculator/) |
| `ireland_maternity_leave_pay` | Ireland: each parent’s take-home pay in the year of maternity/paternity/parent’s leave against a normal year (Maternity Benefit €299 a week in 2026, €309 from 2027; taxed but no USC or PRSI), the household gap and a monthly saving target. | [page](https://decisionscalc.com/tools/ireland-maternity-benefit-calculator/) |
| `ireland_help_to_buy` | Ireland: Help to Buy refund for a first-time buyer of a new build or self-build: the lesser of €35,000 (contracts from 7 October 2026; €30,000 before), 10% of the price, or income tax + DIRT paid in the previous 4 years; price limit €500,000; mortgage at least 70% of the price. Scheme runs to the end of 2029. | [page](https://decisionscalc.com/tools/ireland-help-to-buy-calculator/) |
| `ireland_capital_gains_tax` | Ireland: capital gains tax on a disposal (shares, crypto, property other than your home): 31% for disposals from 7 October 2026 (33% before), 33% on development land, €1,270 annual exemption, losses, and the payment deadline (15 December for January–November disposals). Not for Irish/EU ETFs or funds, which pay exit tax. | [page](https://decisionscalc.com/tools/ireland-cgt-calculator/) |
| `ireland_myfuturefund_pension` | Ireland: MyFutureFund (pension auto-enrolment, started January 2026): what you, your employer and the State pay in (1.5/1.5/0.5% rising to 6/6/2% by year 10, on pay up to €80,000) and the projected pot at retirement. | [page](https://decisionscalc.com/tools/ireland-myfuturefund-calculator/) |
| `ireland_where_to_put_savings` | Ireland: compare where a lump sum ends up after tax over a number of years: State Savings (tax-free), a bank deposit (DIRT 33%), ETFs (exit tax with 8-year deemed disposal), shares (CGT 31%) and a pension (tax relief). Growth for market products is an assumption you set. | [page](https://decisionscalc.com/tools/ireland-savings-investment-calculator/) |
| `uk_stamp_duty_england_ni` | UK: Stamp Duty Land Tax for England and Northern Ireland at 2026/27 rates, band by band: standard, first-time buyer relief (nil to £300,000, up to £500,000) or additional property (+5% on every band), plus the 2% non-resident surcharge. | [page](https://decisionscalc.com/tools/uk-stamp-duty-calculator/) |
| `scotland_lbtt` | Scotland: Land and Buildings Transaction Tax at 2026/27 rates, band by band, with first-time buyer relief (nil band to £175,000) or the 8% Additional Dwelling Supplement. | [page](https://decisionscalc.com/tools/scotland-lbtt-calculator/) |
| `wales_ltt` | Wales: Land Transaction Tax at 2026/27 rates, band by band (nil band £225,000 for everyone; no first-time buyer relief) or the higher rates for additional properties. | [page](https://decisionscalc.com/tools/wales-ltt-calculator/) |
| `canada_ei_maternity_parental` | Canada (outside Quebec): EI maternity and parental benefits for 2026: 55% of insurable earnings up to $729 a week (standard) or 33% up to $437 (extended), 15 weeks maternity, parental weeks, one-week waiting period. | [page](https://decisionscalc.com/tools/canada-ei-benefit-calculator/) |
| `quebec_qpip` | Quebec: QPIP (RQAP) parental insurance for 2026 for both parents: basic or special plan, birth or adoption, earnings up to $103,000, weekly amounts and totals, with the shareable weeks split between parents. | [page](https://decisionscalc.com/tools/quebec-qpip-calculator/) |
| `australia_private_health_rebate_mls` | Australia: private health insurance rebate (1 April 2026 – 31 March 2027) and Medicare Levy Surcharge for 2026–27 by income tier, single or family, and age band: whether hospital cover saves you tax. | [page](https://decisionscalc.com/tools/australia-private-health-rebate-calculator/) |
| `new_zealand_kiwisaver` | New Zealand: KiwiSaver balance at 65 under the 2026 rules (default and employer minimum 3.5%, 4% from April 2028; government contribution 25c per $1 up to $260.72; ESCT on employer contributions; PIR tax on returns). Returns are an assumption you set. | [page](https://decisionscalc.com/tools/kiwisaver-calculator/) |
| `parental_leave_income_gap` | Statutory parental leave pay for a birth parent and the income gap against normal pay (gross, before tax) in the UK (Statutory Maternity Pay), Ireland (Maternity Benefit), Canada (EI), Quebec (QPIP) or Australia (Parental Leave Pay), with an optional employer top-up. | [page](https://decisionscalc.com/parental-leave-planner/) |
| `uk_voluntary_ni_from_abroad` | UK State Pension for people living outside the UK: which gap years (2020–21 to 2026–27) can still be filled with voluntary National Insurance after the 6 April 2026 change, at Class 2 (£3.65/wk, years to 2025–26 only) or Class 3 (£18.40/wk), each year’s cost and 5 April deadline, and the State Pension gain (1/35 of £241.30 a week per year, up to 35 years) with payback. | [page](https://decisionscalc.com/tools/uk-voluntary-ni-abroad-calculator/) |

## What is in this repository

- `src/lib/agent-tools.ts`: the tool definitions (input schemas, which calculation each runs, sources).
- `src/lib/mcp-server.ts` + `functions/mcp.ts`: the stateless MCP server (JSON-RPC: initialize, tools/list, tools/call, ping)
  running as a Cloudflare Pages Function.
- `src/lib/webmcp.ts`: the same tools registered for in-browser agents (WebMCP) on decisionscalc.com.
- `src/lib/calc/*.ts`: the calculations, each with its official sources in the header and a test file reproducing the
  government's own worked examples where one exists. Run `npm install && npm test`.

This is a read-only mirror of the code running on decisionscalc.com, published so it can be audited.
Licence: source available, all rights reserved (see `LICENSE.md`). Using the hosted endpoint is free.

Results are general information, not financial, tax or legal advice. The relevant government department decides.