QuantCalc Retirement Engine — Claude plugin
Gives Claude the retirement engine behind quantcalc.app, so a projection is computed rather than estimated.
A language model cannot run thousands of correlated return paths against a spending plan and get the odds right. It can ask something that can.
Privacy policy · Terms · Support: hello@quantcalc.app · Documentation
Install
Install from the Claude plugin directory. The plugin installs switched off, and you enable it when you want it. Step-by-step instructions are in SETUP.md. To use the server without the plugin, add it as a custom connector:
https://mcp.quantcalc.app
What's in the plugin
- Connector: the hosted QuantCalc engine over streamable HTTP. No account or sign-in is needed.
- Skill
retirement-projections: loads when a plan, withdrawal rate or success rate comes up. It keeps the assumptions attached to every number and flags differences that fall inside the margin of error. - Skill
setup: connection steps, what a licence key changes, and troubleshooting.
Tools
| Tool | Returns |
|---|---|
run_retirement_projection |
Success rate, ending-portfolio distribution, and the assumptions that produced them |
run_tax_aware_projection |
The recommended withdrawal order and Roth-conversion programme, its present-value advantage and range against traditional-first, and the after-tax success rate, with federal and state tax, RMDs, IRMAA and Social Security taxation paid from the portfolio. With move_state (state, year, month) it plans a move to another state: the old state's tax before the move year, a part-year return in each state in the move year, the new state's after it, and the lifetime state tax compared with staying and with moving now |
compare_return_assumptions |
The same plan under each published capital market assumption set |
list_return_assumption_sources |
Which assumption sets the engine carries, and what each publisher provides |
explain_methodology |
What the engine models and what it deliberately leaves out |
estimate_2026_tax_return |
A 2026 federal and state return estimate: the refund or amount owed, the main Form 1040 lines, the state tax, every default assumed and what is not modelled. Needs a QuantCalc PRO or Tax Season Pass licence key |
optimize_social_security_claiming |
The tax-aware plan run at every Social Security claiming age from 62 to 70 on the same simulated markets: each age's success rate and median paired difference against the plan, and the best age with its 10th–90th percentile range. Needs a QuantCalc PRO licence key |
state_tax_in_every_state |
One household's 2026 state income tax in all 50 states and DC, ranked from lowest to highest, with each state's difference from the state it lives in now, the federal tax (the same in every state), the county taxes included, every default assumed and what is not modelled. Military retirement pay goes in military_pension (not pension): a taxable pension on the federal return, and in each state that state's own military retirement rule (exempt, capped, age-tested or credited); on a joint return it follows spouse_split like the pension. Needs a QuantCalc PRO or Tax Season Pass licence key |
All eight are read-only: they compute and return, and change nothing. Inputs are not kept after the run, except that a failed request is kept for two days to diagnose it.
What comes back with every number
A success rate is meaningless without its assumptions, and a summary will drop a caveat it was not handed explicitly. So each result states:
- 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 rate;
- the income it assumed, including when it assumed none;
- whether a correlation matrix had to be adjusted before running;
- a plain warning when a run is not precise enough to show a client;
- for the tax-aware tool: the spending convention (after tax — what the household keeps), every default assumed for an input that was not given, and the tax items the engine does not model.
- for the every-state ranking: the engine versions, the federal tax it used for every state, the county taxes the state figures include, and every default assumed (spouse's age, how a couple's income is split, a private pension).
Licence key
Optional. Without one, projections run at 2,000 paths (the 95% interval around a
success rate is about ±1.5 points) and the tax-aware tool returns the first
retirement year of its year-by-year schedule. A QuantCalc PRO key raises
that to 10,000 paths (about ±0.7) and returns the full schedule. The tax engine
itself — withdrawal order, Roth conversions, state tax — needs no key. Three
tools need a key: estimate_2026_tax_return and state_tax_in_every_state
run on the licensed federal and state tax APIs and need a PRO or Tax Season
Pass key (without one they return nothing and point to the free web pages,
https://quantcalc.app/2026-tax-return-calculator/ and
https://quantcalc.app/best-states-to-retire-for-taxes/), and
optimize_social_security_claiming needs a PRO key. The same
key also unlocks the portfolio optimizer, glide paths, custom capital market
assumptions and multi-period planning in the
QuantCalc app. Those features are not tools in
this plugin.
Set it in the plugin's configuration. It is sent as a connection header and never passes through the conversation.
Privacy
The server receives only the inputs of each tool call, never the conversation. A random session identifier is used to count runs for each installation. A licence key is removed before anything is logged. Details are in section 6 of the privacy policy.
Not advice
QuantCalc is calculation software, not financial advice. Methodology and the source of every figure: https://quantcalc.app/methodology.html. Tax scope and its explicit exclusions: https://quantcalc.app/tax-methodology/.
Licence
MIT — see LICENSE. This repository contains the plugin manifest,
skills and documentation. The engine itself is a hosted service, published to the Official
MCP Registry as app.quantcalc/retirement-engine under a DNS-verified
namespace.