## Documentation Index

Fetch the complete documentation index at: [/llms.txt](https://docs.withflex.com/llms.txt)

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

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](https://mcp.withflex.com/).

## 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](https://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](https://dashboard.withflex.com/). 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](https://docs.withflex.com/developer-guides/integration/mcp/authentication#test-mode) for the full behavior.

## 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](https://support.claude.com/en/articles/11175166-get-started-with-custom-connectors-using-remote-mcp) 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.

## Claude Code

For developers using [Claude Code](https://claude.com/claude-code) in the terminal.

- OAuth (recommended)
- API key

Run:

```bash
claude mcp add flex --transport http https://mcp.withflex.com/api/mcp/oauth
```

The first time you call a Flex tool, Claude Code will open a browser to sign in. Subsequent sessions reuse the token.

Create or copy an API key from the [API keys page](https://dashboard.withflex.com/apikeys) in your Flex Dashboard. Use an `fsk_test_…` key for experimentation.

```bash
claude mcp add flex --transport http https://mcp.withflex.com/api/mcp \
  --header "Authorization: Bearer fsk_YOUR_API_KEY"
```

🧪 Heads up — with the API key path, the key prefix encodes the mode: `fsk_test_…` always hits test data, `fsk_…` always hits live. There’s no per-call test-mode flag. See [Authentication](https://docs.withflex.com/developer-guides/integration/mcp/authentication) for details.

Confirm the connection from any prompt:

```bash
List the MCP tools available from Flex.
```

## 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](https://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:

| Field                   | Value                                     |
|-------------------------|-------------------------------------------|
| **Transport**           | HTTP (streamable)                        |
| **OAuth URL**          | `https://mcp.withflex.com/api/mcp/oauth`|
| **API key URL**        | `https://mcp.withflex.com/api/mcp`      |
| **API key header**     | `Authorization: Bearer fsk_…`           |

A minimal JSON config (the shape most clients accept) looks like:

```json
{
  "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](https://mcp.withflex.com/) generates the exact config snippet.

## Next steps

[**Try sample prompts** \
\
Copy-paste prompts for support, reconciliation, refunds, and reporting.](https://docs.withflex.com/developer-guides/integration/mcp/tools)

[**Authentication & test mode** \
\
How OAuth and API keys compare, and how to stay in test mode safely.](https://docs.withflex.com/developer-guides/integration/mcp/authentication)

[**Security best practices** \
\
Scope your API keys and rotate credentials before going live.](https://docs.withflex.com/developer-guides/integration/mcp/security)