Claude Desktop

Checked on 2026-11-06 against modelcontextprotocol.io: connect local servers, claude.com: custom connectors and the mcp-remote README.

Claude Desktop adds remote servers as custom connectors, which sign in with OAuth. Its config file starts local (stdio) servers only, so an API key needs a local bridge.

Sign in with OAuth

Add Crossmart as a custom connector with the URL https://mcp.crossmart.io/mcp and choose Sign in. Custom connectors are shared by claude.ai, Claude Desktop and the mobile apps; the steps are in the claude.ai guide.

Or connect with an API key

Create a key (how). The config file opens from Settings → Developer → Edit Config:

OS	Path
macOS	~/Library/Application Support/Claude/claude_desktop_config.json
Windows	%APPDATA%\Claude\claude_desktop_config.json
Linux	~/.config/Claude/claude_desktop_config.json

mcp-remote is a small open-source stdio proxy that forwards to a remote server and adds headers. It needs Node.js. It is a third-party project, not part of Claude or Crossmart; pin a version you’ve reviewed if your security policy asks for it.

{
  "mcpServers": {
    "crossmart": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote",
        "https://mcp.crossmart.io/mcp",
        "--header",
        "x-api-key:${CROSSMART_API_KEY}"
      ],
      "env": { "CROSSMART_API_KEY": "cm_…" }
    }
  }
}

Write x-api-key:${CROSSMART_API_KEY} without a space after the colon: the mcp-remote README notes that Claude Desktop on Windows does not escape spaces inside args.

You can also run Crossmart’s own local MCP server; see MCP server → Claude Desktop.

Check

Restart Claude Desktop. The tools menu in a new chat lists crossmart with its tools.

Install the skill

Zip the skills/crossmart folder (the zip must contain the crossmart folder with SKILL.md inside), then Customize → Skills → + → Upload a skill. Skills need code execution turned on (Settings → Capabilities). See Using skills in Claude and the Crossmart skill.