Connect a client - O nosso app

The endpoint


URL	`https://app.onosso.app/v1/mcp`
Method	`POST`
Transport	MCP over HTTP, stateless: one JSON-RPC message per request, answered as `application/json`
Protocol versions	`2025-06-18`, `2025-03-26`
Authentication	`Authorization: Bearer onss_live_…`

Every request carries the token in the Authorization header. A request without it, or with a key that is malformed, unknown or revoked, gets an HTTP 401 (see Errors). When you create a token, the dialog that shows the key also shows each setup below with the key already in it, ready to copy. Here, replace onss_live_… with your key.

Claude Code

claude mcp add --transport http onosso https://app.onosso.app/v1/mcp \
  --header "Authorization: Bearer onss_live_…"

Add --scope user to have it in every project. claude mcp list shows whether it connected.

Claude Desktop

Claude Desktop reaches a remote server that takes a header through mcp-remote, which needs Node.js. Open Settings › Developer › Edit Config and add the server to claude_desktop_config.json:

claude_desktop_config.json

{
  "mcpServers": {
    "onosso": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://app.onosso.app/v1/mcp",
        "--header",
        "Authorization:${ONOSSO_AUTHORIZATION}"
      ],
      "env": {
        "ONOSSO_AUTHORIZATION": "Bearer onss_live_…"
      }
    }
  }
}

The key goes in env rather than in args because some systems split an argument at its space. Restart Claude Desktop afterwards.

Cursor

Add the server to ~/.cursor/mcp.json, or to .cursor/mcp.json in one project:

mcp.json

{
  "mcpServers": {
    "onosso": {
      "url": "https://app.onosso.app/v1/mcp",
      "headers": {
        "Authorization": "Bearer onss_live_…"
      }
    }
  }
}

claude.ai

claude.ai connects through a custom connector. Sending a header from a custom connector is in beta, and the header is entered by the organization’s admin when the connector is added:

In Settings › Connectors, choose Add custom connector.
Enter https://app.onosso.app/v1/mcp as the URL.
Under the request headers, add Authorization with the value Bearer onss_live_….

The header is the same for everyone who uses the connector, so every one of them acts as the person who created the token. Add it only where you are the one who uses it.

ChatGPT

ChatGPT is not listed: its connectors accept only OAuth, and this MCP server does not offer OAuth yet.

​The endpoint

​Claude Code

​Claude Desktop

​Cursor

​claude.ai

​ChatGPT

The endpoint

Claude Code

Claude Desktop

Cursor

claude.ai

ChatGPT