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By Fruit Stand Team · September 6, 2026 · Guides The Fruit Stand Fund Returns MCP server lets you pull trailing and calendar-year returns for 32,000+ US funds and ETFs straight into a Claude conversation. This guide walks through adding it to the Claude Desktop app as a custom connector, authenticated with your API key. There’s no OAuth today — the server authenticates with an API key sent as a Bearer token in a request header. That one detail trips people up, so read the callout in Step 3 carefully.

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Before you start

You’ll need two things:
  • A paid Claude plan. Custom connectors are available on Claude Pro, Max, Team, and Enterprise, not the free tier.
  • A Fruit Stand API key. If you don’t have one yet, grab a free key below. If you already have an account, open your dashboard to copy it.

Get a free API key

New to Fruit Stand? Our pricing page has a free tier that’s enough to get started — no card required.

View your API keys

Already have an account? Copy your API key from your subscriptions dashboard.

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Step 1: Open the custom connector dialog

In the Claude Desktop app, go to Settings → Connectors, scroll to the bottom, and click Add custom connector.

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Step 2: Name the connector and enter the server URL

Give the connector a name you’ll recognize in your connectors list, then enter the Fruit Stand MCP server URL:
Click Continue.
Add custom connector dialog with the name Fruit Stand Mutual Fund & ETF Returns and the server URL https://api.fruitstand.dev/mcp

Name the connector and paste the Fruit Stand MCP server URL.

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Step 3: Set authentication to None and add your API key header

On the next screen, under Authentication, select None — the server uses an API key rather than OAuth. Then, under Request headers, add one header:
  • Header name: authorization
  • Value: your API key, prefixed with Bearer (see the warning below)
  • Leave Required checked.
In the value field, type Bearer — the word “Bearer” followed by a single space — before your API key. The header value is sent exactly as you enter it, so the space after Bearer is required. A bare key, or Bearer with no space, will fail to authenticate.✅ Correct: Bearer zpka_xxxxxxxxxxxxxxxxxxxxxxxxxxxx_xxxxxxxx❌ Wrong: zpka_xxxxxxxxxxxxxxxxxxxxxxxxxxxx_xxxxxxxx❌ Wrong: Bearerzpka_xxxxxxxxxxxxxxxxxxxxxxxxxxxx_xxxxxxxx
Click Add.
Custom connector authentication step with None selected and an authorization request header containing a Bearer token

Select None for authentication, then add an 'authorization' header set to 'Bearer '.

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Step 4: Confirm the connection and tools

Back on the Connectors page, the connector shows as connected with its tools listed under Tool permissions. You’ll see the Fund Returns tools — SearchFunds, GetFund, GetTrailingReturns, GetCalendarReturns, BatchTrailingReturns, and BatchCalendarReturns. Set them to Always allow (or leave them to prompt) depending on how much you want Claude to ask first.
Connected Fruit Stand connector showing six fund returns tools under Tool permissions

Once connected, the Fund Returns tools appear under Tool permissions.

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Step 5: Try it out

Start a new chat and ask something the data can answer, for example:
Search for funds matching “total stock market” and show me the 1-, 5-, and 10-year trailing returns for the closest match.
Claude will call the Fruit Stand tools and answer from live data.

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Troubleshooting

Nearly always the Bearer prefix. Re-open the connector’s request header and confirm the value is Bearer + a single space + your key, with no extra spaces before or after. Because the value is hidden after saving, the quickest fix is to delete the header and re-add it.
Custom connectors require a paid Claude plan (Pro, Max, Team, or Enterprise). On the free tier the option isn’t shown.
Open your subscriptions dashboard to view and copy your key. Need one? Start free on the pricing page.
Questions? Reach out at contact@fruitstand.dev.