Household CFO

Ask Alexa+ “Can we afford this?” and get a real answer from your family’s budget. Household CFO is an MCP server that answers money questions by voice and never spends without asking.

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Inspiration

I have always been very interested in personal finance.Juggling multiple loans and helping parents back in india means watching my money closely and making some good decisions. I was working with spreadsheets for years and this year i decided to build a product. So i built XSPEND, a personal finance and expense tracking app that helps people see where their money goes. The next step I kept thinking about was meeting families where they already are. A lot of money questions come up at home, in the middle of something else: Can we do soccer camp this month? Are we on track with dining? What are we still paying for that nobody uses? Alexa+ is already in millions of the homes, so I wanted to bring personal finance data to it as a voice extension. Household CFO lets a PFM app like XSPEND, or any other finance app or aggregator, answer those questions by voice. And because voice assistants are starting to buy things for us, I built it so it never spends or cancels anything without a clear yes.

What it does

Household CFO is an MCP server for Alexa+. You can ask:

  • "How are we doing on our budget this month?"
  • "Can we afford soccer camp for $240?" (yes, stretch or no, with the reasons)
  • "Buy soccer cleats for $80." (it asks you first)
  • "Cancel Peloton." (it asks, and mentions it hasn't been used in 74 days)
  • "Remember, no new subscriptions until December." (and it brings that up later)

How I built it

The server is TypeScript with the official MCP SDK. The money logic lives in small, tested functions, and the tools just call them.

  • Every purchase and cancellation goes through a guardrail that asks the user first, either with an MCP confirm form or a one-time token tied to that exact action. I published it as an open-source library, mcp-guardrails.
  • It runs on Amazon Bedrock AgentCore behind Amazon Cognito sign-in, and the household is saved in DynamoDB so it's remembered between conversations.
  • The Alexa+ console still says "Coming soon", so I built a small Alexa+ simulator. You talk, Claude on Amazon Bedrock picks the tools on the live server, and the answer is spoken back with an Echo Show style card.
  • In a real setup, the data would come from where the family's money already lives, like a PFM app such as XSPEND or an aggregator like Plaid.

Why it matters

For many families, Amazon is where a big share of everyday purchases happen, and with lots of small orders it's easy to lose track of whether you're under or over budget. Household CFO connects a family's budget from a finance app like XSPEND to Alexa+, so every voice purchase is checked against what the family can actually afford. Your budget becomes your purchasing power. Families stay in control of what gets bought, and that control is what builds trust in shopping by voice across Amazon's devices and services.

Challenges I ran into

  • AWS setup - Account policies blocked services I needed and limited me to one region, so I had to work around them.
  • Model access - The newest model wasn't available on my account, and a missing form came back as a confusing "not found" error.
  • Good spoken answers - At first the assistant read out a generic summary no matter what I asked. It took a few rounds to get it to answer the exact question in a sentence or two.

Accomplishments that I'm proud of

It works end to end by voice: I ask a question out loud, and the answer comes from a live MCP server running on AWS.

  • It never spends money without a yes. A confirmation for $80 cleats can't be reused to buy a $1,500 TV.
  • It remembers. A decision made in one conversation comes back in a brand new one, because it's saved in DynamoDB.
  • I turned the guardrails into an open-source library, mcp-guardrails, that any MCP server can use.
  • It has 66 tests, and I kept the money logic simple enough that every answer can be checked.

What I learned

  • How MCP works end to end, including elicitation, which is new in the latest spec.
  • How to deploy and run it on AWS.
  • That the safety part is the interesting part. Letting an assistant act on money is easy. Making sure it only acts when a person really meant yes takes real design.

What's next for Household CFO

  • A real Alexa+ add-on once the console opens.
  • Connecting real data, read-only, starting with XSPEND.

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