Run the engine from inside Claude
A language model cannot run ten thousand correlated return paths, a Guyton-Klinger guardrail rule, or a whole-retirement search over tax-aware withdrawal orders and Roth conversions and be right about it. It can ask something that can. This connector gives Claude the same engine the app runs, so when you ask for a projection you get a computation with its assumptions attached rather than a plausible paragraph.
Connect it
In Claude, add a custom connector with this URL:
https://mcp.quantcalc.app
- Open Settings → Connectors in Claude.
- Choose Add custom connector.
- Paste the URL above and save.
No account and no signup. If you hold a QuantCalc PRO licence, supply the key as the connector's authorisation token and runs go to full precision. The key is held at the connection, never passed as part of the conversation.
What it can do
| Tool | What it returns |
|---|---|
run_retirement_projection |
Success rate, the ending-portfolio distribution, and the assumptions that produced them. |
run_tax_aware_projection |
The recommended withdrawal order and Roth-conversion programme for a household whose accounts are split by tax type, its present-value advantage and range against drawing traditional first, the same-market-path breakdown of that advantage (tax paid, tax still owed at the end, unfunded spending — parts that add up to it), and the after-tax success rate — with federal and state income tax, Social Security taxability, required minimum distributions and Medicare surcharges paid from the portfolio year by year. |
compare_return_assumptions |
The same plan under each published capital market assumption set, so you can see how far the answer moves with the forecast used. |
list_return_assumption_sources |
Which assumption sets the engine carries and which components each publisher provides. |
explain_methodology |
What the engine models and what it deliberately leaves out. |
estimate_2026_tax_return |
A household's 2026 federal and state return from its income, deductions, withholding and estimated payments: the federal and state refund or amount owed, the main Form 1040 lines and the state's taxable income and tax, with every default assumed and what is not modelled — the same figures as the 2026 tax return calculator. Needs a connected licence (PRO or the Tax Season Pass). An estimate, not a filed return and not tax advice. |
Every tool is read-only. Nothing is stored, and no client data is written anywhere.
What comes back with the number
A success rate is meaningless without the assumptions behind it, and an assistant summarising a result will drop a caveat it was not handed explicitly. So every result states, in the response itself:
- the return model that actually ran — reported by the engine, not by the request;
- the number of paths, and the real trial count behind the success rate;
- the income it assumed including when it assumed none, because an unstated Social Security figure moves a plan more than most inputs;
- whether a correlation matrix had to be adjusted before the run;
- a plain warning when a run is not precise enough to put in front of a client;
- for the tax-aware tool, the spending convention the run used — spending is after tax, what the household keeps — and every default that was assumed because it was not given (state, cost basis, horizon, Medicare age, charitable distributions, the spouse's age);
- what the tax engine does not model — NUA, estate and inheritance tax, federal credits, and wages, self-employment income and the §199A deduction (the planner prices those only for Wages and Self-employment life events, which the connector does not send) — stated in the result, not only on this page;
Limits
Without a licence, runs use 2,000 paths — enough that the 95% interval around a success rate is roughly a point and a half wide, which is a figure you can reason with. The tax-aware tool is included without a licence, and each installation has 40 runs a day; a tax-aware run counts as one run. A PRO licence raises every run to 10,000 paths, returns the tax tool's full year-by-year schedule instead of its first retirement year, and in the app unlocks the portfolio optimizer, glide paths, custom capital market assumptions and multi-period planning, none of which the connector exposes. The 2026 return estimate runs on the licensed federal and state tax APIs, so it needs a connected licence (PRO or the Tax Season Pass); without one it computes nothing and points to the free web calculator.
QuantCalc is calculation software, not financial advice. What the engine models and what it deliberately leaves out — NUA, estate tax and federal credits among them — is written down in the tax methodology and the full methodology.
Support
Questions, or something not behaving: [email protected]. Data handling is covered by the privacy policy.