Walnut MCP connector: connect your portfolio to Claude, ChatGPT, or Codex
Last updated July 2026
Short answer
Walnut is an MCP connector for investors. It lets Claude, ChatGPT, or Codex read and analyze your investment baskets and your connected brokerage portfolio, and build or edit baskets, in plain language. Your holdings stay read-only and it never places trades, those stay at your broker. You add one URL, sign in with your Walnut account, and approve access.
What is an MCP connector?
MCP (the Model Context Protocol) is an open standard that lets an AI assistant securely call external tools and read external data. An MCP connector is the bridge between the assistant and a specific service. Walnut's connector exposes your portfolio to the assistant as a set of tools it can call, so you can ask questions in plain English and the assistant fetches live answers from your account instead of guessing.
If you want the background first, see what an MCP connector is and the roundup of MCP connectors for investing.
What Walnut's MCP connector does
Once connected, your assistant can work with your real portfolio, not just public market data. That is the difference: it reads the holdings you actually own and the baskets you have built. The connector exposes:
- Read your baskets and portfolio. List every basket, inspect one, and read your connected brokerage holdings.
- Analyze performance and drift. See how a basket is tracking versus SPY, how far each holding has drifted from its target weight, and which positions are most off target.
- Get rebalance suggestions. Ask what trades would bring a basket back to its target weights (descriptive math you can review, not an order).
- Build and edit baskets, with your approval. Research an idea in chat and turn it into a basket with target weights. Walnut saves it as a basket you own and review.
Everything about your holdings is read-only, and building a basket never buys or sells anything on its own. Trade execution stays at your broker, where you approve it.
How to connect Walnut to Claude, ChatGPT, or Codex
There is nothing to download, no API key, and no config file. Add one server URL as a custom connector, sign in with your Walnut account, and approve access. The server URL is:
https://walnutinvest.com/api/connector/mcp
Claude
In Claude Desktop or claude.ai, open Settings, Connectors and choose Add custom connector. Enter the name Walnut and the URL above, click Connect, and sign in. Prefer the terminal? In Claude Code run claude mcp add walnut --transport http https://walnutinvest.com/api/connector/mcp, then /mcp and authenticate. See the full walkthrough for connecting a brokerage to Claude.
ChatGPT
Turn on Developer Mode, go to Settings, Apps, choose Create app, and add the server URL, then sign in to Walnut. Custom MCP connectors in ChatGPT require a paid plan with Developer Mode enabled. See connecting a brokerage to ChatGPT.
Codex
In Codex, go to Settings, MCP servers, select Streamable HTTP, and add the URL. In the Codex CLI, run codex mcp add walnut --url https://walnutinvest.com/api/connector/mcp.
Any client that supports remote MCP servers (Cursor and others) works the same way: add the URL over Streamable HTTP and sign in.
Is it safe to connect your portfolio to an AI?
Three things keep it safe. Access to your holdings is read-only. You authenticate through your own Walnut account using OAuth, so you never hand the assistant your broker password. And you approve access before anything is shared, and can disconnect at any time. The connector cannot move money or place trades. For a deeper look, see is it safe to connect your brokerage to an AI.
How Walnut compares to other MCP connectors
MCP connectors fall into a few groups: broker-execution connectors for placing orders, market-data connectors for public prices, and portfolio connectors like Walnut that read your real holdings. Here is where Walnut fits:
| Connector | Connects | Read or trade | Best for |
|---|---|---|---|
| Alpaca MCP | An Alpaca brokerage account | Read and trade | Developers who want order execution |
| Walnut | Your baskets and connected US brokerage holdings | Read and analyze (builds baskets, never auto-trades) | Everyday investors who want AI help with their real portfolio |
| Market-data MCP (Alpha Vantage, Polygon) | Public quotes and fundamentals | Read-only market data | Prices and indicators, not your holdings |
| Build your own | Whatever you code | Depends on your build | Engineers with time to maintain it |
For the full, honest comparison across execution, data, and portfolio connectors, see the best MCP connectors for brokerages roundup, and the broader guide to connecting a brokerage to an AI assistant.
The bottom line
Walnut is the MCP connector that gives Claude, ChatGPT, or Codex a read-only, plain-language view of your real portfolio and baskets, plus the ability to build baskets you review. It adds one URL, needs no code, and never places trades. If your broker has no built-in AI, or its AI cannot see across your whole portfolio, Walnut is the layer that adds one. See which brokers have an AI assistant for where that gap is.
Connect your portfolio to your AI assistant
Create a free Walnut account, then add the connector in Claude, ChatGPT, or Codex. No download, no API key, no trades.
Get your connectorFAQ
What is the Walnut MCP server URL?
The Walnut MCP server is https://walnutinvest.com/api/connector/mcp. You add it as a custom connector in Claude, ChatGPT, or Codex, then sign in with your Walnut account and approve access.
Can Claude or ChatGPT see my portfolio?
Yes, once you connect the Walnut MCP connector and approve access, your assistant can read your investment baskets and your connected brokerage holdings. Access is read-only for your holdings, and you sign in with your own Walnut account, so no broker password is ever shared with the AI.
Does the connector place trades?
No. The connector is read-only for your holdings and never places trades. Building or editing a basket from chat creates a draft in Walnut for you to review; any actual buying or selling still happens at your broker, initiated by you.
Which AI assistants work with it?
Claude (Desktop, claude.ai in the browser, and Claude Code), ChatGPT (with Developer Mode), Codex and the Codex CLI, Cursor, and any client that supports remote MCP servers.
Do I need to write any code?
No. There is nothing to download, no API key, and no config file. You add one URL as a custom connector, sign in, and approve. A CLI one-liner is available for Claude Code and Codex CLI if you prefer the terminal.
Is it free?
The connector is free to use. You need a Walnut account, which is free to create.
Which brokers can I connect?
Walnut connects the major US brokerages for read-only holdings, so your assistant can analyze what you actually own. Trade execution stays at your broker.
Is it safe to connect my brokerage to an AI?
The connection is read-only for your holdings, you authenticate through your own Walnut account with OAuth (not by handing the AI your broker login), and you approve access before anything is shared. The assistant cannot move money or place trades through Walnut.
How is this different from a market-data MCP server?
A market-data MCP (like Alpha Vantage or Polygon) gives an assistant public quotes and fundamentals. Walnut connects YOUR real holdings and baskets, so the assistant can answer questions about your specific portfolio, not just the market.
Can I build baskets by chatting?
Yes. You can ask your assistant to research an idea and build a basket with target weights. Walnut creates it as a basket you own and can review; it never trades automatically.
What tools does the Walnut connector expose?
Read tools for listing and inspecting baskets, reading the connected portfolio, checking drift, getting rebalance suggestions and performance versus SPY, and comparing baskets, plus write tools (with your approval) to create and edit baskets.
Walnut is an informational tool, not a registered investment adviser. Nothing here is investment advice, and connecting an AI assistant does not change where your money is held or who executes your trades.