Get Started with Horizon3.ai-Hosted MCP Server

Set up the MCP Server hosted by Horizon3.ai in your IDE or other AI client.

Prerequisites

• An IDE or AI client that supports streamable HTTP and OAuth 2.1 (e.g. VS Code, Cursor, Windsurf)
• A modern browser for completing the OAuth login

Setting Up Visual Studio Code

To set up the Horizon3-hosted MCP Server in Visual Studio Code:

1. Open the command palette in VS Code.
2. Click Show and Run Commands.
3. Run the command MCP: Add Server.
4. Select HTTP (HTTP or Server-Sent Events) as the type.
5. Enter the server URL:
   • US: https://mcp.horizon3ai.com/mcp
   • EU: https://mcp.horizon3ai.eu/mcp
6. Provide a name for the server (for example, horizon3-mcp-server).

    # Visual Studio Code creates an `mcp.json` file (or adds to it if it already exists) with the information you just entered
        {
        "servers": {
            "horizon3-mcp-server": {
                "url": "https://mcp.horizon3ai.com/mcp",
                "type": "http"
            }
        },
        "inputs": []
        }

1. After clicking Allow, login to your Horizon3 Portal Account following the redirect. Once you successfully login, close the browser and you're ready to get started!

Client Compatibility

The Horizon3 MCP Server works with MCP-compliant clients that support both OAuth 2.1 authentication and HTTP streamable transport. This includes:

• VS Code with MCP extensions - Fully compatible
• Claude Code - Fully compatible
• Claude Desktop - Currently has some known compatibility issues
• Gemini CLI - Full compatible
• Windsurf - Fully compatible

Set Up Other IDEs or Clients

1. In your client of choice, enter the server URL:
   • US: https://mcp.horizon3ai.com/mcp
   • EU: https://mcp.horizon3ai.eu/mcp
2. Use streamable HTTP as the transport mode
3. Begin the OAuth login process when prompted and complete using your NodeZero credentials after being redirected

Manual Set Up

To set up the Horizon3-hosted MCP Server for other IDEs or clients manually, create an mcp.json file in your workspace or home directory with an entry for the MCP Server:

{
   "servers": {
       "horizon3-mcp-server": {
           "url": "https://mcp.horizon3ai.com/mcp",
           "type": "http"
       }
   },
   "inputs": []
}

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