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Google CalendarCAUTION

mcp/takumi0706/google-calendar-5
MCP server by takumi0706 · Audited 2026-10-08
⚑ Report / re-scanSource ↗

Google Calendar MCP server for Claude Desktop integration

Verdict
CAUTION
Grade
B
Trust score
85 /100
Exposed tools
12 8r · 4w · 0d
Transport
—
License
MIT
Stars
59
01

Overview

From the repository's own README, as read at the audited commit. Badges and raw HTML are left out.

🔔 VERSION UPDATE NOTICE 🔔 Version 2.0.0 moves to MCP protocol revision 2026-07-28 and implements PKCE on the OAuth flow. It requires Node.js 20 or newer. See the version history below for the full list of changes.

[](README.ja.md) [](README.md)

Project Overview

Google Calendar MCP Server is an MCP (Model Context Protocol) server implementation that enables integration between Google Calendar and Claude Desktop. This project enables Claude to interact with the user's Google Calendar, providing the ability to display, create, update, and delete calendar events through natural language interaction.

Core Features

  • Google Calendar integration: Provides a bridge between Claude Desktop and the Google Calendar API
  • MCP implementation: Follows the Model Context Protocol specification for AI assistant tool integration
  • OAuth2 authentication: Handles the Google API authentication flow securely
  • Event management: Supports comprehensive calendar event operations (get, create, update, delete)
  • Color support: Ability to set and update event colors using colorId parameter
  • STDIO transport: Uses standard input/output for communication with Claude Desktop

Technical Architecture

This project uses:

  • TypeScript: For type-safe code development
  • MCP SDK: Uses @modelcontextprotocol/server v2 (protocol revision 2026-07-28, with the 2025 revisions still served for older clients)
  • Google API: Uses googleapis for Google Calendar API access
  • Hono: Lightweight and fast web framework for th
Read from source at commit 16ef5b41ccfeOBSERVED · 2026-10-08
02

Connect

Built from this server's own package name, version and transport as found in its source — not copied from anyone's documentation, so it cannot drift against a page we do not control. Replace the environment placeholders with a token scoped to the least it needs.

claude-code
claude mcp add google-calendar-mcp --env AUTH_HOST=${AUTH_HOST} --env AUTH_PORT=${AUTH_PORT} --env GOOGLE_CLIENT_SECRET=${GOOGLE_CLIENT_SECRET} --env TOKEN_ENCRYPTION_KEY=${TOKEN_ENCRYPTION_KEY} -- npx -y @takumi0706/[email protected]
claude-desktop
{
  "mcpServers": {
    "google-calendar-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@takumi0706/[email protected]"
      ],
      "env": {
        "AUTH_HOST": "${AUTH_HOST}",
        "AUTH_PORT": "${AUTH_PORT}",
        "GOOGLE_CLIENT_SECRET": "${GOOGLE_CLIENT_SECRET}",
        "TOKEN_ENCRYPTION_KEY": "${TOKEN_ENCRYPTION_KEY}"
      }
    }
  }
}
03

Exposed tools (12)

8 read · 4 write · 0 destructive.

ToolRiskDescription
cancel_eventreadCancel an existing event
create_meetingwriteCreate a new meeting
create_recurring_meetingwriteCreate a recurring meeting
find_free_timereadFind available time slots
find_meeting_conflictsreadCheck for scheduling conflicts
prepare_for_todayreadGet today\
primary_calendarreadUser\
reschedule_eventreadReschedule an existing event
schedule_around_eventwriteSchedule new events around existing ones
user_calendarsreadList of all calendars accessible to the user
view_upcoming_eventsreadShow my upcoming events
weekly_schedule_overviewwriteGet a weekly schedule overview
04

Trust audit

CAUTIONgrade B · trust 85/100 Install with care. The audit found things worth knowing before you trust its output.

LayerWhat it checksResult
L0Provenance & inventoryPASS
L1Static analysis of the codeWARN
L2Instruction surface (what it tells the agent)PASS
L3Class-specific surfacePASS
L4Behavioural (sandbox)SKIPPED

What the source does

Filesystem
none-observed
Network
none-observed
Shell
none-observed
Dependencies
not all pinned
Secrets in source
found

Findings (12)

MEDIUMInformation disclosure · disclose.log_secret · CWE-209, CWE-532
src/auth/token-manager.ts:103
logger.debug(`Token stored for user: ${userId}, expires: ${new Date(expiryTime).toISOString()}`);
MEDIUMInformation disclosure · disclose.log_secret · CWE-209, CWE-532
src/auth/token-manager.ts:124
logger.debug(`No token found for user: ${userId}`);
MEDIUMInformation disclosure · disclose.log_secret · CWE-209, CWE-532
src/auth/token-manager.ts:133
logger.debug(`Token expired for user: ${userId}`);
MEDIUMInformation disclosure · disclose.log_secret · CWE-209, CWE-532
src/auth/token-manager.ts:171
logger.debug(`Token removed for user: ${userId}`);
MEDIUMHard-coded secrets · secret.private_key · CWE-798, CWE-321
src/__tests__/utils/security-sanitizer.test.ts:60
'private_key: -----BEGIN PRIVATE KEY-----'
LOWFilesystem / path · fs.traversal · CWE-22, CWE-59
src/__tests__/auth/oauth-handler.test.ts:2
import { OAuthHandler } from '../../auth/oauth-handler';
LOWFilesystem / path · fs.traversal · CWE-22, CWE-59
src/__tests__/auth/oauth-handler.test.ts:3
import { tokenManager } from '../../auth/token-manager';
LOWFilesystem / path · fs.traversal · CWE-22, CWE-59
src/__tests__/auth/oauth-handler.test.ts:5
jest.mock('../../utils/logger', () => ({
LOWFilesystem / path · fs.traversal · CWE-22, CWE-59
src/__tests__/auth/token-manager.test.ts:2
import { tokenManager } from '../../auth/token-manager';
LOWFilesystem / path · fs.traversal · CWE-22, CWE-59
src/__tests__/auth/token-manager.test.ts:5
jest.mock('../../utils/logger', () => ({
LOWSupply chain · supply.unpinned · CWE-829, CWE-1357
package.json
@hono/node-server, @modelcontextprotocol/server, dotenv, googleapis, hono, open, zod, @eslint/js
Why it matters. 17 dependency range(s) float
Fix. pin exact versions or ship a lockfile
INFOPrompt injection · prompt.credential_read · CWE-94, CWE-1427
CONTRIBUTING.md:16
cat > .env << EOL
Why it matters. asks the agent to read credentials

Gates applied: no_behavioural_pass.

Audited 2026-10-08 · audit v0.4.1 · source sha 16ef5b41ccfefull audit observations/trust-audit/mcp-server/takumi0706__google-calendar-5.json · Report an issue / request a re-scan
05

Audit history

Every audit this server has had. A grade with a past is a grade somebody is still checking.

DateSourceVerdictGradeScoreChange
2026-10-0816ef5b41ccfeCAUTIONB85first audit
06

Questions

What is the Google Calendar MCP server?

Google Calendar MCP server for Claude Desktop integration

What tools does Google Calendar expose?

12 in total: 8 read-only, 4 that write, and 0 that can delete or overwrite. Every one is listed on this page with its risk.

Is Google Calendar safe to connect to an agent?

With care. The audit graded it B (85/100) and found 12 things worth knowing before you trust this server, listed below with the exact line each was found on.

What credentials does Google Calendar need?

It reads AUTH_HOST, AUTH_PORT, GOOGLE_CLIENT_SECRET, TOKEN_ENCRYPTION_KEY and USE_MANUAL_AUTH from the environment. Give it a token scoped to the least it needs — an agent that can be talked into calling a tool can be talked into calling it with your credentials.

How current is this page?

The grade is for one exact copy of the source (16ef5b41ccfe), read on 2026-10-08. The repository is watched and re-audited when it changes.

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