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MCP server

Connecting clients

Every client points at the same URL, https://app.klang.ai/api/mcp (or your dedicated URL from Settings → Developers → MCP). What differs is how you authenticate. The guides below cover the common clients.

Pick your client

Jump straight to setup for your tool — each guide is a couple of steps.

arrow_forward Claude Web & desktop arrow_forward ChatGPT Custom connector arrow_forward Claude Code Terminal arrow_forward Cursor API key arrow_forward Vibe Mistral CLI arrow_forward Other clients Windsurf, Zed, Goose…

Two ways to authenticate

Klang's MCP server accepts either method on the same endpoint. Pick whichever the client supports best:

  • OAuth sign-in. The client opens a browser on first use, you approve a consent screen, and it stores and refreshes tokens on its own. Nothing to paste. This is the smoothest path where the client implements it well: Claude, ChatGPT, and Claude Code all do.
  • API key. You create an sk_ key in Settings → Developers → API keys and put it in an Authorization: Bearer header. Use this for clients that can't run the OAuth flow (Vibe) or don't drive it reliably yet (Cursor's current releases). The same key works on the REST API.

Claude (web and desktop)

Add Klang as a custom connector and it works across both Claude.ai and the Claude desktop app. Custom connectors are available on the Free, Pro, Max, Team, and Enterprise plans (Free is limited to one). Anthropic's custom connector guide is the canonical reference; the short version:

  1. On Pro or Max, open Settings → Connectors, click +, and choose Add custom connector.
  2. Paste the server URL https://app.klang.ai/api/mcp and click Add. Leave Advanced settings empty — Klang runs the OAuth flow itself, so no client ID or secret is needed.
  3. Click Connect and sign in to Klang when the browser prompt appears.
  4. In a chat, open the + menu in the composer, choose Connectors, and toggle Klang on for that conversation.

Team and Enterprise: an owner first adds the connector under Organization settings → Connectors (Add → hover Custom → Web), then each member enables it from their own Settings → Connectors with Connect.

Claude Desktop config file

As an alternative on desktop, add the server to claude_desktop_config.json (Claude Desktop → Settings → Developer → Edit config):

claude_desktop_config.json
{ "mcpServers": { "klang": { "type": "http", "url": "https://app.klang.ai/api/mcp" } } }

Restart Claude Desktop. The first Klang tool call prompts you to sign in.

ChatGPT

ChatGPT connects to remote MCP servers through developer mode, available on its paid plans. OpenAI's connect to ChatGPT guide is the canonical reference; to add Klang:

  1. Turn on developer mode: open Settings → Apps & Connectors → Advanced settings and enable Developer mode. A Create button then appears under Settings → Apps & Connectors.
  2. Go to Settings → Connectors → Create and fill in the required fields: Connector name (Klang), a short Description, and the Connector URL https://app.klang.ai/api/mcp.
  3. Click Create. ChatGPT opens the Klang sign-in so you can approve access — it uses OAuth, so there's no key to paste.
  4. In a new chat, click + in the composer, choose More, and pick Klang from the list.

ChatGPT custom connectors authenticate with OAuth only — there's no field for a static Authorization header, so use the sign-in flow rather than an API key. If you later change which tools Klang exposes, refresh the cached list from Settings → Connectors → select Klang → Refresh.

Claude Code

Add the server from the terminal. Claude Code runs the OAuth sign-in for you:

Terminal
claude mcp add --transport http klang \ https://app.klang.ai/api/mcp

Run /mcp inside Claude Code to trigger the sign-in and check the connection. Add --scope project to share the server with a repo via .mcp.json.

With an API key

To skip the browser flow (handy for headless or CI use), pass a key in a header instead:

Terminal
claude mcp add --transport http klang \ https://app.klang.ai/api/mcp \ --header "Authorization: Bearer sk_YOUR_KEY"

Cursor

Cursor's current releases don't reliably start the OAuth flow for remote servers, so the dependable setup is an API key. Create one in Settings → Developers → API keys, then add Klang to ~/.cursor/mcp.json (global) or .cursor/mcp.json in a project:

~/.cursor/mcp.json
{ "mcpServers": { "klang": { "url": "https://app.klang.ai/api/mcp", "headers": { "Authorization": "Bearer sk_YOUR_KEY" } } } }

Open Settings → MCP and confirm Klang shows its tools. If you would rather use OAuth, bridge through mcp-remote (see other clients), which runs the sign-in for Cursor.

Vibe

Mistral's Vibe CLI authenticates to remote MCP servers with static headers only, so use an API key. Create one in Settings → Developers → API keys and add a server block to ~/.vibe/config.toml (or ./.vibe/config.toml in a project):

~/.vibe/config.toml
[[mcp_servers]] name = "klang" transport = "streamable-http" url = "https://app.klang.ai/api/mcp" headers = { Authorization = "Bearer sk_YOUR_KEY" }

Open the /mcp view to confirm klang lists its tools. Define the server only once: two blocks with the same name make Vibe fail to load it.

Any other client

Klang exposes a standard MCP server over Streamable HTTP (JSON-RPC) at https://app.klang.ai/api/mcp, authenticated with OAuth or a Bearer key. Below is an mcp.json to connect using your API key — if your client supports OAuth, you can remove the headers field:

mcp.json
{ "mcpServers": { "klang": { "type": "http", "url": "https://app.klang.ai/api/mcp", "headers": { "Authorization": "Bearer sk_YOUR_KEY" } } } }
key Stdio-only client, or want OAuth where the client won't drive it? Bridge to the remote endpoint with mcp-remote: npx mcp-remote https://app.klang.ai/api/mcp — it runs the OAuth flow and speaks stdio to the client.