Poke Plaid

A custom MCP server that hooks your investment portfolio into Poke via Plaid.

Why this exists. Poke can't see your Wealthsimple / brokerage portfolio — there's no public API and no built-in Plaid integration:

"we don't support plaid out of the box right now … but since you're a cracked dev, you could easily build a custom mcp server that hooks into plaid's api and upload it." — Poke

So here it is. Link any brokerage/retirement account through Plaid once, point Poke at this server, and ask things like "what's my portfolio worth?", "what are my biggest winners?", or "how much did I get in dividends this month?".

It works in two modes:

• Mock mode (default, no credentials needed) — serves a realistic sample Wealthsimple-style portfolio so you can wire up Poke and try every tool right now.
• Plaid mode — set PLAID_CLIENT_ID / PLAID_SECRET and link your real accounts.

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Tools exposed to Poke

Tool	What it does
check_connection	Confirms the data source is connected and lists linked institutions.
list_accounts	All linked investment/brokerage/retirement accounts + last-known balances.
get_balances	Up-to-date balances (forces a fresh read from the institution when supported).
portfolio_summary	Net-worth-style snapshot: total value + unrealized gain/loss by currency, per-account breakdown, allocation by asset type, and top holdings.
list_holdings	Every position: ticker, name, quantity, price, market value, cost basis, unrealized gain/loss. Filter by account / min value; sort by value or gain.
list_investment_transactions	Buys, sells, dividends, contributions, fees, transfers over a date range.
get_dividend_income	Total dividends over a period, broken down by security and currency, plus each payment.

All tools are read-only and never move money.

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Quick start (mock mode — 60 seconds)

npm install
npm run dev

The server starts on http://localhost:3000. Verify it end-to-end:

npm run test:mcp    # boots the server, drives it with a real MCP client, calls every tool

Then connect it to Poke. Everything works with sample data until you add Plaid credentials.

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Using your real portfolio (Plaid)

1. Get Plaid API keys

Create a free account at dashboard.plaid.com and grab your client_id and sandbox/production secret from Developers → Keys. Investments data requires the Investments product (request access in the dashboard if it isn't already enabled).

2. Configure

cp .env.example .env

Fill in at least:

PLAID_CLIENT_ID=your_client_id
PLAID_SECRET=your_secret
PLAID_ENV=sandbox            # or: production
PLAID_PRODUCTS=investments
PLAID_COUNTRY_CODES=US,CA    # CA covers Wealthsimple
TOKEN_ENCRYPTION_KEY=<a long random string>   # encrypts access tokens at rest
MCP_API_KEY=<a random string>                  # require this key on the /mcp endpoint

3. Link an account

npm run dev

Open http://localhost:3000/setup, click Connect, and complete Plaid Link. Your bank credentials go straight to Plaid — never to this server. The resulting access token is encrypted and stored in ./data/items.json.

Sandbox shortcut (no browser): with PLAID_ENV=sandbox you can link a test institution from the CLI:

npm run link:sandbox            # default sandbox institution
npm run link:sandbox ins_XXXXX  # a specific one

You can link multiple institutions; all of them are aggregated across every tool.

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Connecting to Poke

Poke talks to this server over Streamable HTTP at /mcp. Pick one:

Option A — Local tunnel (recommended for personal use)

Keeps your financial data and Plaid tokens on your machine. Start the server, then in another terminal:

npx poke@latest tunnel http://localhost:3000/mcp -n "Plaid Portfolio"

Leave both running. Poke syncs the tools automatically. Say "check my portfolio connection" in Poke to confirm.

Option B — Hosted server

Deploy somewhere public (see Deployment), then add it at poke.com/integrations/new:

• Name: Plaid Portfolio
• MCP Server URL: https://your-host.example.com/mcp
• API Key: the value of MCP_API_KEY (sent as a Bearer token)

…or via the CLI:

npx poke@latest mcp add https://your-host.example.com/mcp -n "Plaid Portfolio" -k "$MCP_API_KEY"

Option C — Shareable recipe (Poke Kitchen)

To package this for others, create a recipe at poke.com/kitchen with this server as a required MCP integration and some onboarding context (e.g. first message: "What's my portfolio worth?").

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Deployment

Any host that runs a Node service works (Fly.io, Render, Railway, a VPS, …).

docker build -t poke-plaid-mcp .
docker run -p 3000:3000 --env-file .env -v "$PWD/data:/app/data" poke-plaid-mcp

The image sets HOST=0.0.0.0 and NODE_ENV=production, so it won't start without MCP_API_KEY (by design). For a hosted deployment set: MCP_API_KEY, TOKEN_ENCRYPTION_KEY, SETUP_TOKEN, and PUBLIC_BASE_URL=https://your-host. Then link accounts at https://your-host/setup?token=YOUR_SETUP_TOKEN.

Persist /app/data (the volume above) so your linked-account tokens survive restarts. On platforms with an ephemeral filesystem, use a mounted disk/volume.

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Configuration reference

Var	Default	Notes
PORT	3000	HTTP/MCP port.
HOST	127.0.0.1	Bind interface. Loopback by default (LAN-safe, works with poke tunnel). Set 0.0.0.0 for containers/hosting.
NODE_ENV	development	In production, the server refuses to start if bound publicly without MCP_API_KEY, or using Plaid without TOKEN_ENCRYPTION_KEY.
PUBLIC_BASE_URL	http://localhost:PORT	Also seeds the Host/Origin allowlist. Set to your public URL when hosted.
MCP_API_KEY	(empty)	If set, /mcp requires Authorization: Bearer <key> (or x-api-key). Required for internet-facing use.
SETUP_TOKEN	(empty)	Token required to use /setup* (pass as ?token=). Required to expose setup on a public host.
ALLOWED_HOSTS / ALLOWED_ORIGINS	(empty)	Extra allowlist entries (loopback + PUBLIC_BASE_URL are always allowed).
ALLOW_ANY_HOST	false	Disable Host-header allowlisting (behind a Host-rewriting proxy). Origin checks stay on.
PLAID_CLIENT_ID / PLAID_SECRET	(empty)	Leave blank for mock mode.
PLAID_ENV	sandbox	sandbox or production.
PLAID_PRODUCTS	investments	Comma-separated Plaid products.
PLAID_COUNTRY_CODES	US,CA	Comma-separated country codes.
PLAID_APP_NAME	Poke Portfolio	Shown in Plaid Link.
TOKEN_STORE_PATH	./data/items.json	Where encrypted tokens live.
TOKEN_ENCRYPTION_KEY	(empty)	AES-256-GCM key for tokens at rest. Required in production w/ Plaid.

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Security

This server touches your financial data, so it's locked down by default:

• Read-only. No tool can move money — only account/holding/transaction reads.
• Loopback by default. Binds to 127.0.0.1, so a local install is never exposed to your LAN. poke tunnel still reaches it. Hosting requires HOST=0.0.0.0.
• /mcp auth via MCP_API_KEY (timing-safe Bearer check). In production, the server refuses to start if bound publicly without a key.
• /setup* auth via SETUP_TOKEN. Without a token, setup is only reachable from localhost (and disabled entirely on a public host).
• DNS-rebinding / cross-origin protection. Requests with a disallowed Origin are rejected, and the Host header is allowlisted — a malicious website in your browser can't drive the server. Server-to-server callers (Poke, the tunnel) are unaffected.
• Tokens encrypted at rest with AES-256-GCM (TOKEN_ENCRYPTION_KEY); token file is written 0600. The data/ dir is git-ignored — never commit it.
• Secrets are redacted from logs. Your bank login is entered in Plaid Link and never touches this server. TLS is provided by the tunnel / your host.
• npm audit: 0 known vulnerabilities.

For an internet-facing deployment, set all of: HOST=0.0.0.0, NODE_ENV=production, MCP_API_KEY, TOKEN_ENCRYPTION_KEY, SETUP_TOKEN, and PUBLIC_BASE_URL.

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How it works

Poke ──HTTP(S) /mcp──▶  Express + MCP (Streamable HTTP, stateless)
                             │
                             ▼
                        PortfolioProvider
                        ┌────────────┴────────────┐
                     PlaidProvider            MockProvider
                     (real Plaid API)      (sample portfolio)

The MCP tool layer is provider-agnostic: it always receives normalized holdings/accounts/transactions, so swapping mock ↔ Plaid changes nothing about the tools Poke sees.

Project structure

src/
  index.ts              # bootstrap
  server.ts             # Express app: /mcp (auth), /health, /setup
  mcp.ts                # MCP server + tool definitions
  portfolio-math.ts     # portfolio + dividend aggregation (pure functions)
  config.ts             # env config, mock/plaid mode selection
  logger.ts             # redacting JSON logger
  store.ts              # encrypted access-token storage
  providers/
    types.ts            # normalized domain types + PortfolioProvider interface
    plaid.ts            # Plaid client, normalization, Link helpers
    mock.ts             # realistic sample data
    index.ts            # provider selection
  routes/link.ts        # Plaid Link setup endpoints
  public/setup.html     # Plaid Link setup UI
scripts/
  sandbox-link.ts       # link a Plaid sandbox institution (no browser)
  test-mcp.ts           # end-to-end MCP smoke test

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Notes on Wealthsimple

Wealthsimple has no public portfolio API, which is the whole reason for this server. Plaid's coverage of Wealthsimple's investments data varies by account type and region — if Plaid can link your Wealthsimple account with the Investments product, this server surfaces it. If not, you can link any other Plaid-supported brokerage, and the mock mode always works for building/testing the Poke experience.

License

MIT