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Setup by Tool

Narnia's MCP server is a local, loopback-only Streamable HTTP endpoint (http://127.0.0.1:5244/mcp) served by the same always-on process as the web UI — it is not a stdio process that your MCP client launches itself. No API key or authentication is required; it only reads from your local ~/.copilot/ files.

Start the server first

Every snippet below assumes Narnia is already running (see Getting Started). GitHub Copilot CLI's sessionStart hook keeps it running automatically once installed as a plugin; other clients don't know to start it for you, so start it yourself first — otherwise the client will show a connection error or zero tools.

GitHub Copilot CLI

Installing Narnia as a plugin (copilot plugin install ncosentino/narnia) ships a working .mcp.json in the plugin bundle — nothing to hand-edit:

{
  "mcpServers": {
    "narnia": {
      "type": "http",
      "url": "http://127.0.0.1:5244/mcp",
      "tools": ["*"]
    }
  }
}

The same plugin's sessionStart hook also relaunches the server at the start of every session if it isn't already up.

VS Code

Add to .vscode/mcp.json in your workspace (or run MCP: Add Server from the Command Palette and choose HTTP):

{
  "servers": {
    "narnia": {
      "type": "http",
      "url": "http://127.0.0.1:5244/mcp"
    }
  }
}

Cursor

Add to .cursor/mcp.json in your project root (or a user-level ~/.cursor/mcp.json to make it available everywhere):

{
  "mcpServers": {
    "narnia": {
      "url": "http://127.0.0.1:5244/mcp"
    }
  }
}

Cursor infers the transport from the presence of url (no command or type needed) — this is its documented format for a remote-style server.

Visual Studio

Add to %USERPROFILE%\.mcp.json (available to every solution) or <SolutionDir>\.mcp.json (that solution only). Requires Visual Studio 2022 17.14+ or Visual Studio 2026:

{
  "servers": {
    "narnia": {
      "url": "http://127.0.0.1:5244/mcp"
    }
  }
}

Claude Desktop

Claude Desktop's own config file (claude_desktop_config.json) only launches stdio servers directly. Its URL-based "Custom Connectors" feature is a claude.ai (web) integration built for internet-hosted, authenticated servers — it doesn't apply to a loopback-only local server like Narnia's.

The practical workaround is mcp-remote, a small stdio-to-HTTP bridge process, referenced from claude_desktop_config.json (~/Library/Application Support/Claude/ on macOS, %APPDATA%\Claude\ on Windows):

{
  "mcpServers": {
    "narnia": {
      "command": "npx",
      "args": ["mcp-remote", "http://127.0.0.1:5244/mcp"]
    }
  }
}

Protocol compatibility

Narnia's MCP server speaks the 2026-07-28 MCP revision and still negotiates down-level with clients on 2025-11-25, 2025-06-18, and 2025-03-26. Version negotiation is automatic — there is nothing to configure.

MCP clients periodically adopt newer revisions of the specification. If a client updates to a revision your installed Narnia predates, the connection fails at the handshake with an error like:

failed to negotiate MCP lifecycle: JSON-RPC error: -32000:
Bad Request: The MCP-Protocol-Version header value '2026-07-28' is not supported.

Despite the wording, this is not an authentication or network problem — Narnia's endpoint requires no credentials. It means the client is asking for a newer protocol revision than the running server understands. Fix it by updating Narnia to the latest release (see Getting Started), then restarting the server so the new build is listening.

See Configuration for environment variable overrides to customize the database path and session state directory.