How to integrate Google Calendar MCP with OpenCode

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How to integrate Google Calendar MCP with OpenCode

This guide explains how to connect Google Calendar MCP to OpenCode using Composio Connect, which simplifies OAuth, API changes, and reliability concerns.

There are two ways to set this up:

Also integrate Google Calendar with

Why use Composio?

Composio provides a single MCP server or CLI tool that exposes a set of meta-tools, allowing you to:

  • Connect to 1,000+ apps with on-demand tool loading, so you do not fill your LLM context window with unnecessary tool definitions.
  • Use programmatic tool calling through a remote Bash tool, letting LLMs write their own code to handle complex tool chaining. This reduces back-and-forth for frequent tool calls.
  • Handle large tool responses outside the LLM context to keep conversations lean.

Connect Google Calendar with OpenCode

Option 1: Using Composio CLI

1. Install Composio CLI

Install the Composio CLI, authenticate, and initialize your project:

bash
# Install the Composio CLI
curl -fsSL https://composio.dev/install | bash

# Authenticate with Composio
composio login

During login, you will be redirected to the sign-in page. Finish the flow and you are all set.

Composio CLI authorization screen

2. Authorize Google Calendar

Once the CLI is installed, it is essentially done. Give OpenCode access to your apps with these steps:

  1. Launch OpenCode.
  2. Prompt it to "Authenticate with Google Calendar Composio".
  3. Complete the authentication and authorization flow, and your Google Calendar integration is all set.
  4. Start asking anything you want.

Option 2: Using Composio MCP

You can also connect Google Calendar to OpenCode by adding Composio as an MCP server through the OpenCode CLI.

1. Add the Composio MCP server

bash
opencode mcp add

This launches an interactive prompt.

2. Fill in the fields

FieldValue
Namecomposio
Typeremote
URLhttps://connect.composio.dev/mcp
Require OAuthYes
Have client IDNo
OpenCode MCP server interactive prompt for Composio

Alternatively, you can skip the interactive prompt and paste the configuration directly into your OpenCode config file.

Open your global OpenCode config:

bash
open ~/.config/opencode/opencode.json

Add this under the mcp key and save the file.

bash
{
  "mcp": {
    "composio": {
      "type": "remote",
      "url": "https://connect.composio.dev/mcp",
      "enabled": true
    }
  }
}

3. Authenticate

Authenticate the Composio MCP server you just added:

bash
opencode mcp auth composio

This opens a browser session. Authorize Composio and you are done.

Composio browser authorization for OpenCode MCP

4. Verify installation

bash
opencode mcp list

5. Connect Google Calendar with OpenCode

Now, in the chat, ask the agent to connect to Google Calendar or give it any Google Calendar-related task.

For example, ask it to:

  • "Create a meeting with the marketing team"
  • "List all events scheduled for next week"
  • "Delete tomorrow’s canceled event from your calendar"

It will prompt you to authenticate and authorize access to Google Calendar.

That is it. Composio tools are now available in OpenCode, and your Google Calendar account is ready to use.

Supported Tools & Triggers

Tools
Triggers
Insert Calendar into ListInserts an existing calendar into the user's calendar list.
Update Calendar List EntryUpdates an existing entry on the user\'s calendar list.
Delete CalendarDeletes a secondary calendar.
Update CalendarUpdates metadata for a calendar.
Clear CalendarClears a primary calendar.
Create EventCreates an event on a google calendar, needing rfc3339 utc start/end times (end after start) and write access to the calendar.
Delete eventDeletes a specified event by `event id` from a google calendar (`calendar id`); this action is idempotent and raises a 404 error if the event is not found.
Create a calendarCreates a new, empty google calendar with the specified title (summary).
Get Event InstancesReturns instances of the specified recurring event.
List EventsReturns events on the specified calendar.
Move EventMoves an event to another calendar, i.
Watch EventsWatch for changes to events resources.
Find eventFinds events in a specified google calendar using text query, time ranges (event start/end, last modification), and event types; ensure `timemin` is not chronologically after `timemax` if both are provided.
Find free slotsFinds free/busy time slots in google calendars for specified calendars within a defined time range (defaults to the current day utc if `time min`/`time max` are omitted), enhancing busy intervals with event details; `time min` must precede `time max` if both are provided.
Query Free/Busy InformationReturns free/busy information for a set of calendars.
Get Google CalendarRetrieves a specific google calendar, identified by `calendar id`, to which the authenticated user has access.
Get current date and timeGets the current date and time, allowing for a specific timezone offset.
List ACL RulesRetrieves the list of access control rules (acls) for a specified calendar, providing the necessary 'rule id' values required for updating specific acl rules.
List Google CalendarsRetrieves calendars from the user's google calendar list, with options for pagination and filtering.
Patch CalendarPartially updates (patches) an existing google calendar, modifying only the fields provided; `summary` is mandatory and cannot be an empty string, and an empty string for `description` or `location` clears them.
Patch EventUpdates specified fields of an existing event in a google calendar using patch semantics (array fields like `attendees` are fully replaced if provided); ensure the `calendar id` and `event id` are valid and the user has write access to the calendar.
Quick Add EventParses natural language text to quickly create a basic google calendar event with its title, date, and time, suitable for simple scheduling; does not support direct attendee addition or recurring events, and `calendar id` must be valid if not 'primary'.
Remove attendee from eventRemoves an attendee from a specified event in a google calendar; the calendar and event must exist.
List SettingsReturns all user settings for the authenticated user.
Watch SettingsWatch for changes to settings resources.
Sync EventsSynchronizes google calendar events, performing a full sync if no `sync token` is provided or if a 410 gone error (due to an expired token) necessitates it, otherwise performs an incremental sync for events changed since the `sync token` was issued.
Update ACL RuleUpdates an access control rule for the specified calendar.
Update Google eventUpdates an existing event by `event id` in a google calendar; this is a full put replacement, so provide all desired fields as unspecified ones may be cleared or reset.

Way Forward

Now that Google Calendar is connected, extend your setup by connecting the other apps you already use every day, so your agent can run true cross-app workflows end to end.

  • Connect Calendar to turn threads into scheduled meetings automatically.
  • Connect Slack or Teams to post summaries, approvals, and alerts where your team works.
  • Connect Notion, Linear, Jira, or Asana to convert requests into tickets, tasks, and docs.
  • Connect Drive, Dropbox, or OneDrive to fetch, file, and share attachments without manual steps.

Start with one workflow you do repeatedly, then keep adding apps as you find new handoffs. With everything behind a single MCP endpoint, your agent can coordinate multiple tools safely and reliably in one conversation.

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FAQ

What are the differences in Tool Router MCP and Google Calendar MCP?

With a standalone Google Calendar MCP server, the agents and LLMs can only access a fixed set of Google Calendar tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Google Calendar and many other apps based on the task at hand, all through a single MCP endpoint.

Can I use Tool Router MCP with OpenCode?

Yes, you can. OpenCode fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Google Calendar tools.

Can I manage the permissions and scopes for Google Calendar while using Tool Router?

Yes, absolutely. You can configure which Google Calendar scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

How safe is my data with Composio Tool Router?

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Google Calendar data and credentials are handled as safely as possible.

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Letta
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HubSpot
Agent.ai
Altera
DataStax
Entelligence
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Context
Letta
glean
HubSpot
Agent.ai
Altera
DataStax
Entelligence
Rolai

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