Astrocal

Give your AI agents the power to schedule meetings. The official Model Context Protocol server for Astrocal — the API-first scheduling platform built for developers and AI agents.

Works with Claude Desktop, Cursor, Windsurf, and any MCP-compatible client. Your AI assistant can check availability, book meetings, cancel, reschedule, and manage waitlists — all through natural conversation.

Get your API key | Documentation | API Reference

Why Astrocal for AI Agents?

• Purpose-built for AI — Not a Calendly bolt-on. Astrocal's scheduling API was designed from day one for programmatic and AI-agent access.
• 8 tools, zero config — Check availability, book, cancel, reschedule, list event types, manage waitlists. Everything an agent needs.
• Calendar sync built in — Connects to Google Calendar, Microsoft 365, and CalDAV. Your agent books against real availability.
• Payments included — Stripe Connect integration means your agent can book paid consultations, not just free meetings.
• Sandbox mode — Test with ac_test_* keys. No emails sent, no calendar events created, no charges made.

Quick Start

Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "astrocal": {
      "command": "npx",
      "args": ["-y", "@astrocal/mcp-server"],
      "env": {
        "ASTROCAL_API_KEY": "ac_live_xxxxxxxxxxxxx"
      }
    }
  }
}

Restart Claude Desktop and the scheduling tools will be available immediately.

Other MCP Clients

Install globally:

npm install -g @astrocal/mcp-server

Run:

ASTROCAL_API_KEY=ac_live_xxx astrocal-mcp

Environment Variables

Variable	Required	Description
ASTROCAL_API_KEY	Yes	Your Astrocal API key (get one free)
ASTROCAL_API_URL	No	API base URL (default: https://api.astrocal.dev)
ASTROCAL_DEFAULT_EVENT_TYPE_ID	No	Default event type ID — your agent won't need to specify it on every call

Available Tools

check_availability

Check available time slots for booking.

• event_type_id (string, optional) — Event type to check. Optional if ASTROCAL_DEFAULT_EVENT_TYPE_ID is set.
• start_date (string, required) — Start date in ISO 8601 format (e.g., 2026-03-15)
• end_date (string, required) — End date in ISO 8601 format (e.g., 2026-03-22)
• timezone (string, optional) — IANA timezone (e.g., America/New_York). Defaults to UTC.

create_booking

Book a meeting at a specific time.

• event_type_id (string, optional) — Event type to book. Optional if default is set.
• start_time (string, required) — ISO 8601 datetime (e.g., 2026-03-15T14:00:00Z)
• invitee_name (string, required) — Full name of the person booking
• invitee_email (string, required) — Email address for calendar invitation
• invitee_timezone (string, optional) — IANA timezone. Defaults to UTC.
• notes (string, optional) — Meeting notes (max 1000 characters)

cancel_booking

Cancel an existing booking. The invitee receives a cancellation email automatically.

• booking_id (string, required) — ID of the booking to cancel
• reason (string, optional) — Cancellation reason (max 500 characters)

reschedule_booking

Reschedule a booking to a new time. Check availability first.

• booking_id (string, required) — ID of the booking to reschedule
• new_start_time (string, required) — New time in ISO 8601 format
• reason (string, optional) — Reason for rescheduling (max 500 characters)

list_bookings

List bookings with optional filters.

• status (string, optional) — Filter: confirmed, cancelled, or pending_payment
• limit (number, optional) — Max results (default: 10, max: 100)
• event_type_id (string, optional) — Filter by event type

list_event_types

List available event types that can be booked. No input required.

join_waitlist

Join the waitlist when all slots are full.

• event_type_id (string, required) — Event type to join the waitlist for
• name (string, required) — Full name
• email (string, required) — Email address
• preferred_times (string, optional) — Preferred time ranges or notes

check_waitlist

Check your position on a waitlist.

• waitlist_entry_id (string, required) — Waitlist entry ID returned from join_waitlist

Example Conversation

User: "What meetings can I book?"

Agent: calls list_event_types — "You have two event types: a 30-minute consultation (free) and a 1-hour strategy session ($50)."

User: "Check if next Tuesday at 2pm is free for a consultation"

Agent: calls check_availability — "Tuesday at 2pm is available."

User: "Book it for [email protected]"

Agent: calls create_booking — "Done! Meeting confirmed for Tuesday, March 17 at 2:00 PM UTC with Jane. A calendar invitation has been sent."

User: "Actually, move it to 3pm"

Agent: calls reschedule_booking — "Rescheduled to 3:00 PM. Jane has been notified."

Part of the Astrocal Platform

This MCP server is one of several ways to integrate with Astrocal:

• REST API — Full scheduling API with OpenAPI 3.1 spec
• React SDK (@astrocal/react) — Typed hooks, provider, and booking widget for React apps
• Embeddable Widget (@astrocal/widget) — Drop-in booking UI for any website
• Dashboard — Manage event types, bookings, team members, and billing
• Webhooks — Real-time notifications for booking events

Create a free account to get started.

Links

• Astrocal Website
• Documentation
• API Reference
• Dashboard
• GitHub
• Issues

License

MIT