Connect a client

Every client needs the same two things: the server's URL, https://api.signwithsigil.com/mcp, and an Authorization header with your API key. Create a key for the client first, on the dashboard's API page.

Claude Code

Add it with one command:

claude mcp add --transport http sigil https://api.signwithsigil.com/mcp \
  --header "Authorization: Bearer $SIGIL_API_KEY"

To share the setup with a project without committing the key, put it in the project's .mcp.json and let each person supply SIGIL_API_KEY from their environment:

{
  "mcpServers": {
    "sigil": {
      "type": "http",
      "url": "https://api.signwithsigil.com/mcp",
      "headers": { "Authorization": "Bearer ${SIGIL_API_KEY}" }
    }
  }
}

Run /mcp inside Claude Code to check that sigil is connected and see its tools.

Claude Desktop

Claude Desktop's configuration file starts local servers, so it reaches a remote server with custom headers through the mcp-remote bridge (it needs Node.js). Open Settings → Developer → Edit Config and add:

{
  "mcpServers": {
    "sigil": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://api.signwithsigil.com/mcp", "--header", "Authorization:${SIGIL_AUTH}"],
      "env": { "SIGIL_AUTH": "Bearer sgk_…" }
    }
  }
}

Restart Claude Desktop. The header is passed through an environment variable, without a space after the colon, because some clients split arguments on spaces.

Cursor

Add it to ~/.cursor/mcp.json (every project) or .cursor/mcp.json (one project):

{
  "mcpServers": {
    "sigil": {
      "url": "https://api.signwithsigil.com/mcp",
      "headers": { "Authorization": "Bearer sgk_…" }
    }
  }
}

VS Code

Add it to .vscode/mcp.json. With an input, VS Code asks for the key once and stores it securely, so it is never written in the file:

{
  "inputs": [
    { "type": "promptString", "id": "sigil-key", "description": "Sigil API key", "password": true }
  ],
  "servers": {
    "sigil": {
      "type": "http",
      "url": "https://api.signwithsigil.com/mcp",
      "headers": { "Authorization": "Bearer ${input:sigil-key}" }
    }
  }
}

Other clients

Any client that supports remote MCP servers over Streamable HTTP with custom headers works: give it the URL and the Authorization: Bearer sgk_… header. A client that can only start local (stdio) servers can use the same mcp-remote bridge shown for Claude Desktop.

Test the connection

The MCP Inspector lets you call each tool by hand:

npx @modelcontextprotocol/inspector

Choose the Streamable HTTP transport, enter https://api.signwithsigil.com/mcp, add the Authorization header with Bearer sgk_…, and connect. List Tools shows all ten.

Or check the key and plan with a plain request. A working setup answers the initialize call with the server's name, sigil:

curl https://api.signwithsigil.com/mcp \
  -H "Authorization: Bearer $SIGIL_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"curl","version":"1.0"}}}'

Troubleshooting