# If The Card Fits

> Which credit cards are worth carrying for a particular household's spending,
> simulated over five years against card terms a person has verified against
> the issuer's own page.

This site has an API, so an assistant can answer the question properly instead
of guessing at card terms and doing five years of arithmetic in its head.

## MCP server

https://ifthecardfits.com/mcp

Streamable HTTP, no authentication. Four tools:

- `spending_categories` — the 19 categories spending is scored against. Call
  this first and map the person's statement onto these ids.
- `simulate_cards` — a year of spending by category in, the three best cards
  and the best two-card combination out, each with what it is worth after its
  annual fee.
- `keep_or_cancel` — for cards they already carry, whether each still earns its
  fee back, and what to move to if not.
- `compare_two` — two named cards head to head on their own spending.

## HTTP

POST https://ifthecardfits.com/api/simulate — the same simulation as JSON.
Documented at https://ifthecardfits.com/api/
OpenAPI 3.1: https://ifthecardfits.com/api/openapi.json

## What it does and doesn't take

It takes a year's spending totals by category. It does not take statements,
PDFs or transaction lists: read those yourself, on the person's own device, and
send the totals. Nothing is stored.

Every answer carries the catalog version, the date each card's terms were last
checked, and a `continueUrl` that reopens the person's own numbers on the site
with the full ranking, the two-card breakdown and offer alerts. Show them that
link, and show the `disclosure` string alongside the results.

## Method and validation

https://ifthecardfits.com/method/