Part of the Paid plan. AI agents and API keys come with Paid ($2/month, billed annually at $24), along with up to 20 calendars and unlimited AI stickers.
Server URL: https://reallybigcalendar.com/mcp · Transport: Streamable HTTP · Auth: Authorization: Bearer rbc_…
What you can do with it
Anything you would do by hand, described in plain English. Some favourites:
Because the agent works through your account, it obeys the same rules the app does: your plan's calendar limit, labels, colours, the lot. Events an agent adds are marked "Added by an AI agent" when you open them, so you always know what was you and what was the robot.
Get a key
- Open the app, then Settings → AI Agents & API Keys.
- Give the key a name (the tool that will use it, e.g. "Claude Code") and press Create key.
- Copy the key. It starts with
rbc_and is shown once. You can revoke it from the same screen at any time.
A key has the same access as you do: every calendar on the account, read and write. Treat it like a password. If it leaks, revoke it.
Connect your agent
Replace rbc_YOUR_KEY with the key you just made.
Claude Code
claude mcp add --transport http reallybigcalendar https://reallybigcalendar.com/mcp \
--header "Authorization: Bearer rbc_YOUR_KEY"Add --scope user to make it available in every project.
Codex (OpenAI)
Put the key in your environment as RBC_API_KEY, then add to ~/.codex/config.toml:
[mcp_servers.reallybigcalendar]
url = "https://reallybigcalendar.com/mcp"
bearer_token_env_var = "RBC_API_KEY"Cursor
In .cursor/mcp.json (project) or ~/.cursor/mcp.json (global):
{
"mcpServers": {
"reallybigcalendar": {
"url": "https://reallybigcalendar.com/mcp",
"headers": { "Authorization": "Bearer rbc_YOUR_KEY" }
}
}
}Claude Desktop and other stdio-only clients
Use the mcp-remote bridge. In claude_desktop_config.json:
{
"mcpServers": {
"reallybigcalendar": {
"command": "npx",
"args": ["-y", "mcp-remote", "https://reallybigcalendar.com/mcp",
"--header", "Authorization:${RBC_AUTH}"],
"env": { "RBC_AUTH": "Bearer rbc_YOUR_KEY" }
}
}
}Claude.ai web connectors need OAuth sign-in, which is not available yet.
Tools the agent gets
| Tool | What it does |
|---|---|
get_today | Today's date, so the agent doesn't guess. |
list_calendars | Your calendars, their ids, and how many your plan allows. |
create_calendarrename_calendar | Make or rename a calendar. Creating fails politely when your plan's limit is reached. |
list_events | Events in a calendar, optionally within a date range or by label. |
create_eventcreate_events | Add one event, or up to 100 in one go. Single-day or multi-day, with emoji, colour, label and description. |
update_eventdelete_events | Change or remove events by id. |
list_labelscreate_label | Labels for a calendar. Unknown labels are created automatically when an event uses them. |
list_ideascreate_idea | The undated ideas bar under each year. |
Running it on a schedule
Every create_event accepts an external_id: a stable id from wherever the event came from, such as the source URL. When the same id comes back later the existing event is updated rather than duplicated. That makes repeat runs safe.
So a recurring job that says "search for new Bangkok dharma events and add them, using the source URL as external_id" can run every week and your calendar quietly fills up with what's new. How you schedule it is up to you: Claude Code's scheduled routines, a cron job running claude -p or codex exec, or any automation that can talk to an MCP server.
The fine print
- AI agents and API keys need the Paid plan. If an account goes back to Free, its keys stop working (403) until it upgrades again; nothing is deleted.
- Keys can be created and revoked only from the app while signed in. A key cannot make more keys.
- Requests are rate limited to keep things fair. A normal agent session never gets near the limit.
- Questions or a client that won't connect? Use Contact Us in the app.
