google-calendar-mcp-serviceaccount: Instructions file for Codex

Agent instructions: installing this MCP server

This file is for an AI coding agent helping a human install and configure this repo. Follow it in order. Steps are marked HUMAN (must be done by the person, in their browser — you cannot do these) or AGENT (you do these once the human has provided what the HUMAN steps produce).

1. Google Cloud service account — HUMAN

As of this writing, every step below is free — no billing account or credit card needs to be attached to the Google Cloud project. Tell the human this up front; it's a common point of hesitation. This could change in the future, so don't state it as a permanent guarantee if you're reading this much later than it was written.

The human must:

1. Go to console.cloud.google.com and create a project (any name).
2. Enable the Google Calendar API for that project.
3. Go to Credentials → Create Credentials → Service Account (not "OAuth client ID" — this repo does not use OAuth).
4. Open the created service account → Keys tab → Add Key → Create new key → type JSON. This downloads a .json file.
5. Open Google Calendar, go to the settings of the calendar to use → "Share with specific people" → add the service account's email address (shown on its details page, looks like [email protected]) → permission "Make changes to events".

Ask the human to give you the downloaded JSON file (its contents, or its path if they place it on the target machine themselves) and the ID of the calendar they shared. For someone's own primary calendar, the ID is simply their email address (e.g. [email protected]) — this is not a placeholder, it is the literal, correct value. For any other calendar (a secondary or shared one), the ID is a generated string, found on that calendar's Settings page under "Integrate calendar" → "Calendar ID" (often ending in @group.calendar.google.com). Ask which calendar they shared and get the exact ID from them — do not assume it is primary, and do not guess.