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Stripe MCP: "Operation is not available with secret key type"

Error: Operation 'GetBalance' is not available with secret key type.

What causes it

Stripe's MCP server (mcp.stripe.com) limits some API operations by key type. In our Oct 17 and Oct 18, 2026 tests with a test-mode full-access secret key (sk_test_), creating customers, products, prices and payment links worked, but stripe_api_read refused GetBalance with this message, even though Stripe lists Retrieve balance among supported methods. Stripe's docs say MCP should use OAuth or an agent API key, and that starting in December 2026 Stripe MCP stops accepting full-access secret keys and restricted keys without the Agent tag (they get a 401 with an OAuth challenge). A related message, "Operation 'DeleteCustomersCustomer' is not available", means the operation is not exposed over MCP at all.

How to fix it

  1. Interactive clients (Claude, Cursor, VS Code, ChatGPT): connect with OAuth and pick the sandbox or account and permissions in Stripe's consent screen.
  2. Headless agents: create an agent API key in the Stripe Dashboard (it shows an Agent badge) with only the permissions the agent needs, and send it as Authorization: Bearer. Migrate before November 30, 2026; plain sk_ and untagged rk_ keys stop working on Stripe MCP in December.
  3. Run stripe_api_search first to see which operations your key can use.
  4. For operations not exposed over MCP (for example deleting a customer), use the Stripe Dashboard or the Stripe API directly. We deleted our test customer through the API.

Where we hit it

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