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Documentation Index

Fetch the complete documentation index at: https://docs.withflex.com/llms.txt

Use this file to discover all available pages before exploring further.

Claude using the Flex MCP to create a product
The Flex MCP server is hosted at https://mcp.withflex.com. Pick the client you use below — most paths take less than five minutes. The Claude.ai (web) flow is the most beginner-friendly; Claude Code is the best fit for developers; Cursor, Windsurf, and VS Code each have one-click install links from the Flex MCP landing page.

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Claude.ai (per user)

Works on every paid Claude.ai plan (Pro, Max, Team, Enterprise) and only takes a sign-in.
1

Open Claude.ai connector settings

Go to claude.ai → Settings → Connectors.
2

Add a custom connector

Click Add custom connector, then paste the Flex MCP URL:
https://mcp.withflex.com/api/mcp/oauth
Give it a name (e.g. “Flex”) and click Add.
3

Sign in with your Flex account

Claude will open a browser window to sign in. Use the email/password (or SSO) you use for the Flex Dashboard. Approve the access prompt.
4

Try it

Back in Claude, ask:
Use the Flex MCP to list my five most recent payment intents.
Claude will request approval to call a Flex tool the first time. Allow it once or “for this task,” and you’re connected.
🧪 Heads up — Claude.ai is OAuth, so test vs. live mode is set per call via an api_test_mode parameter the LLM passes to each tool. By default, read tools return live data and write tools require you to specify the mode. See Test mode for the full behavior.

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Claude.ai (workspace admin)

If you’re on a Team or Enterprise plan, an admin can install the Flex connector once for the whole workspace instead of asking every member to add it individually.
1

Open admin Custom Connectors

Follow Anthropic’s Custom Connectors guide to find the admin connector settings.
2

Add Flex

Paste https://mcp.withflex.com/api/mcp/oauth as the connector URL, set the name to “Flex”, and save.
3

Members sign in on first use

Each workspace member will be prompted to authenticate with their own Flex login the first time they use a Flex tool — there’s no shared service account.

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Claude Code

For developers using Claude Code in the terminal. Confirm the connection from any prompt: 
List the MCP tools available from Flex.

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Other MCP clients

The Flex MCP works with any client that supports the Model Context Protocol. For Cursor, Windsurf, VS Code, and Claude Desktop, the easiest path is to visit mcp.withflex.com — pick your client and auth method, then click the one-click install link or copy the generated config. If you’re wiring up a client we don’t list explicitly, here’s what you need:
FieldValue
TransportHTTP (streamable)
OAuth URLhttps://mcp.withflex.com/api/mcp/oauth
API key URLhttps://mcp.withflex.com/api/mcp
API key headerAuthorization: Bearer fsk_…
A minimal JSON config (the shape most clients accept) looks like: 
{
  "mcpServers": {
    "flex": {
      "type": "http",
      "url": "https://mcp.withflex.com/api/mcp/oauth"
    }
  }
}
For the API key path, add a headers object with the Authorization bearer. Tested clients: Claude.ai · Claude Desktop · Claude Code · Cursor · Windsurf · VS Code (GitHub Copilot MCP). For each of these the Flex MCP landing page generates the exact config snippet.

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Next steps

Try sample prompts

Copy-paste prompts for support, reconciliation, refunds, and reporting.

Authentication & test mode

How OAuth and API keys compare, and how to stay in test mode safely.

Security best practices

Scope your API keys and rotate credentials before going live.