Gemini

Google's Gemini Code Assist (VS Code/IntelliJ extension) and the standalone gemini-cli both speak MCP.

Prerequisites

Gemini Code Assist extension installed, or gemini-cli (npm install -g @google/gemini-cli)
A Transactional API token (tk_live_…)

Option A — gemini-cli (one-liner)

If you have gemini-cli installed, this is the fastest path. Paste this single line in your terminal:

gemini mcp add transactional --http https://mcp.transactional.dev --header "Authorization=Bearer tk_live_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"

Verify:

gemini mcp list

Should show transactional with five tools.

Option B — Gemini Code Assist (VS Code / IntelliJ)

For the IDE extension, edit the JSON config directly.

Gemini Code Assist reads MCP servers from a settings.json file.

Path — ~/.gemini/settings.json (global) or .gemini/settings.json in the workspace (project-scoped).

{
  "mcpServers": {
    "transactional": {
      "httpUrl": "https://mcp.transactional.dev",
      "headers": {
        "Authorization": "Bearer tk_live_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
      }
    }
  }
}

Reload the extension (command palette → Gemini Code Assist: Reload MCP Servers). The transactional tools appear in the chat panel.

Use it

In Gemini's chat:

"List my Transactional documents and tell me which is the invoice template."

Gemini calls list_documents, asks for approval, summarizes. Then:

"Generate the invoice PDF — customer Acme Corp, amount 1280.50 €."

It will call get_document first (to learn the exact variables shape your template expects) and then generate_pdf. The PDF URL is printed inline.

"MCP server not responding" — Confirm https://mcp.transactional.dev returns a 405 on GET (the stateless transport rejects non-POST). If it returns 502, our service is down — check the status page.

Tools listed but every call returns unauthorized — Token revoked or copy-pasted with a leading/trailing space. Regenerate from the dashboard.

Gemini won't show MCP tools at all — You're on an older version. Update to the latest extension / gemini-cli build (MCP support landed in 2025).

Next steps