# io.github.deciduus/calendar-mcp (pypi · calendar-mcp-server)

Google Calendar for LLM agents: find, create, update, move, delete events; free/busy; scheduling.

- Trust score: 72/100 (medium)
- Change this week: +3
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-21

## Components

- pypi · `calendar-mcp-server`: 72/100 (this document), [markdown](https://verifymcp.io/servers/deciduus-calendar-mcp/calendar-mcp-server.md), [page](https://verifymcp.io/servers/deciduus-calendar-mcp/calendar-mcp-server)

## Channel facts

- Registry: `pypi`
- Package: `calendar-mcp-server`
- Version: `1.0.1`
- Transport: `stdio`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-09-21.

- **Supply Chain Security**: 100/100
  - No malware found by supply-chain analysis.
  - No known CVEs affecting this package version or its production dependencies.
  - Runs setuptools.build_meta at install time, a recognised native-build step with no shell scripting around it.
  - 3 of 55 dependencies flagged as unhealthy.
- **Provenance & Transparency**: 32/100
  - Source repository is publicly reachable at the declared URL.
  - Provenance check failed: no build-provenance attestation is published.
  - License check failed: no license is declared.
  - Actively maintained (last published 15 days ago).
  - Disclosure check failed: no security disclosure policy was found in the source repository.
- **Schema Quality & AI Usability**: 70/100
  - AI-judged instruction clarity (excellent).
  - Context-footprint check failed: tool/resource definitions use about 2621 tokens (~174/item across 15 items; 15 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 53/100
  - Stability observed for 16 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 71/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 0% of tool parameters carry a description.
  - Structured output schemas are declared (100% of tools); any adoption earns full credit.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - All 1 tool(s) whose name or description implies an irreversible operation declare an MCP destructiveHint annotation.
  - An AI judge read all 16 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a current MCP spec version (2026-07-28).

## Install

### How do I install the io.github.deciduus/calendar-mcp server?

io.github.deciduus/calendar-mcp runs locally as a PyPI package, launched with uvx calendar-mcp-server. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add deciduus-calendar-mcp -- uvx calendar-mcp-server
```

### Cursor

```json
{
  "mcpServers": {
    "deciduus-calendar-mcp": {
      "command": "uvx",
      "args": [
        "calendar-mcp-server"
      ]
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "deciduus-calendar-mcp": {
      "command": "uvx",
      "args": [
        "calendar-mcp-server"
      ]
    }
  }
}
```

### Codex

```bash
codex mcp add deciduus-calendar-mcp -- uvx calendar-mcp-server
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "deciduus-calendar-mcp": {
      "type": "local",
      "command": [
        "uvx",
        "calendar-mcp-server"
      ],
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add deciduus-calendar-mcp --command uvx --arg calendar-mcp-server
```

### Hermes

```yaml
mcp_servers:
  deciduus-calendar-mcp:
    command: "uvx"
    args: ["calendar-mcp-server"]
```

### Netclaw

```json
{
  "McpServers": {
    "deciduus-calendar-mcp": {
      "Transport": "stdio",
      "Command": "uvx",
      "Arguments": [
        "calendar-mcp-server"
      ]
    }
  }
}
```

### Vellum

```bash
assistant mcp add deciduus-calendar-mcp -t stdio -c uvx -a calendar-mcp-server
```

### Other

```json
{
  "mcpServers": {
    "deciduus-calendar-mcp": {
      "command": "uvx",
      "args": [
        "calendar-mcp-server"
      ]
    }
  }
}
```

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-09-20 (score 72, +1)

No change was recorded against any check on this day. Stability & Change Management went from 47 to 50. That category is still filling its 30-day observation window: 14 days of observed history at the previous scan, 15 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-18 (score 71, +1)

No change was recorded against any check on this day. Stability & Change Management went from 40 to 43. That category is still filling its 30-day observation window: 12 days of observed history at the previous scan, 13 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-16 (score 70, +1)

No change was recorded against any check on this day. Stability & Change Management went from 33 to 37. That category is still filling its 30-day observation window: 10 days of observed history at the previous scan, 11 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-14 (score 69, +1)

No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-13 (score 68, +3)

- [functional improvement] Stability: unverified → 0.27

### 2026-09-06 (score 65, +15)

- [security improvement] Malware scan: unverified → pass

### 2026-09-05 (score 50)

First indexed and scored.

## MCP tools (15)

### `list_calendars` (~107 tokens)

List calendars

List the calendars the signed-in user can see, with their IDs and timezones.

Start here whenever the user mentions a calendar other than their own: the
\`id` values returned are what every other tool's `calendar_id` expects.

Args:
    min_access_role: Only return calendars where the user has at least this
        role: 'freeBusyReader', 'reader', 'writer' or 'owner'. Omit for all.

Input parameters:

- `min_access_role`

Output parameters:

- `calendars` (array): The user's calendars.
- `count` (integer): Number of calendars returned.

### `create_calendar` (~43 tokens)

Create a calendar

Create a new secondary calendar owned by the user.

Args:
    summary: Name for the new calendar, e.g. 'Client work'.

Input parameters:

- `summary` (string, required)

Output parameters:

- `access_role`: The user's role: 'owner', 'writer', 'reader', 'freeBusyReader'.
- `description`: Calendar description.
- `id` (string): Calendar ID. Pass this as calendar_id to other tools.
- `primary` (boolean): True for the user's main calendar (also addressable as 'primary').
- `summary`: Calendar name.
- `time_zone`: IANA timezone of the calendar, e.g. 'Europe/Berlin'.

### `find_events` (~181 tokens)

Find events

Search a calendar for events, expanding recurring series into instances.

Use this before any tool that needs an `event_id`. Narrow the window with
\`time_min`/`time_max` rather than raising `max_results`.

Args:
    calendar_id: Calendar to search. 'primary' is the user's own calendar.
    time_min: Inclusive start of the window, ISO 8601 with a UTC offset.
        Without an offset it is read in the calendar's own timezone.
    time_max: Exclusive end of the window, ISO 8601.
    query: Free-text search over title, description, location and attendees.
    max_results: Maximum events to return (default 50).

Input parameters:

- `calendar_id` (string)
- `max_results` (integer)
- `query`
- `time_max`
- `time_min`

Output parameters:

- `calendar_id` (string): Calendar that was searched.
- `count` (integer): Number of events returned.
- `events` (array): The matching events, earliest first.
- `time_zone`: IANA timezone of the calendar that was searched.

### `check_attendee_status` (~92 tokens)

Check attendee RSVPs

Report who has accepted, declined or not yet answered an event invitation.

Args:
    event_id: The event to inspect (from `find_events`).
    calendar_id: Calendar the event lives on.
    attendee_emails: Restrict the report to these addresses. Omit for all.

Input parameters:

- `attendee_emails`
- `calendar_id` (string)
- `event_id` (string, required)

Output parameters:

- `attendees` (array): Attendees and their current RSVP state.
- `calendar_id` (string): Calendar the event lives on.
- `count` (integer): Number of attendees reported.
- `event_id` (string): Event that was checked.

### `query_free_busy` (~122 tokens)

Query free/busy

Get busy intervals for one or more calendars, without revealing event details.

Works for other people's calendars addressed by email, which is how you check
whether someone is free before proposing a time.

Args:
    calendar_ids: Calendar IDs or attendee email addresses to check.
    time_min: Start of the window, ISO 8601 with a UTC offset.
    time_max: End of the window, ISO 8601 with a UTC offset.

Input parameters:

- `calendar_ids` (array, required)
- `time_max` (string, required)
- `time_min` (string, required)

Output parameters:

- `calendars` (array): Per-calendar busy intervals.
- `time_max` (string): End of the queried window, ISO 8601.
- `time_min` (string): Start of the queried window, ISO 8601.

### `analyze_busyness` (~103 tokens)

Analyze calendar load

Summarise how loaded each day is: event count and total scheduled minutes.

Use this to answer "how busy is my week" without listing every event.

Args:
    time_min: Start of the window, ISO 8601.
    time_max: End of the window, ISO 8601.
    calendar_id: Calendar to analyse.

Input parameters:

- `calendar_id` (string)
- `time_max` (string, required)
- `time_min` (string, required)

Output parameters:

- `calendar_id` (string): Calendar that was analysed.
- `days` (array): Per-day totals, in date order.
- `time_max` (string): End of the analysed window, ISO 8601.
- `time_min` (string): Start of the analysed window, ISO 8601.
- `total_duration_minutes` (number): Sum of total_duration_minutes across all days.
- `total_events` (integer): Sum of event_count across all days.

### `project_recurring_events` (~155 tokens)

Project recurring events

Compute future occurrences of recurring events from their recurrence rules.

Unlike `find_events`, this expands the RRULEs locally, so it reaches past the
horizon Google materialises instances for -- useful for "when do my birthdays
/ standups land next year".

Args:
    time_min: Start of the projection window, ISO 8601.
    time_max: End of the projection window, ISO 8601.
    calendar_id: Calendar whose recurring events should be projected.
    event_query: Only project recurring events matching this text, e.g. 'Birthday'.

Input parameters:

- `calendar_id` (string)
- `event_query`
- `time_max` (string, required)
- `time_min` (string, required)

Output parameters:

- `calendar_id` (string): Calendar that was projected.
- `count` (integer): Number of projected occurrences.
- `occurrences` (array): Computed occurrences, earliest first.
- `time_max` (string): End of the projection window, ISO 8601.
- `time_min` (string): Start of the projection window, ISO 8601.

### `create_event` (~243 tokens)

Create an event

Create an event with explicit start and end times, and optional attendees.

For a one-line natural-language description ("coffee with Sam tomorrow at 3")
prefer `quick_add_event`.

Args:
    calendar_id: Calendar to create the event on.
    summary: Event title. Required.
    start_time: Start, ISO 8601 with a UTC offset (e.g. '2026-03-14T15:00:00-04:00').
        Without an offset it is read in the calendar's own timezone.
    end_time: End, ISO 8601, same convention as start_time.
    description: Longer notes for the event body.
    location: Free-text location or meeting link.
    attendee_emails: People to invite. They receive an invitation email
        unless send_notifications is false.
    send_notifications: Whether Google emails the attendees. Default true.

Input parameters:

- `attendee_emails`
- `calendar_id` (string)
- `description`
- `end_time` (string)
- `location`
- `send_notifications` (boolean)
- `start_time` (string)
- `summary` (string)

Output parameters:

- `calendar_id` (string): Calendar the event lives on.
- `event`: The event after the operation.
- `message` (string): One-line human-readable summary of what happened.

### `quick_add_event` (~129 tokens)

Quick-add an event

Create an event from a plain-English phrase, parsed by Google.

Google interprets the date, time and title itself, in the calendar's own
timezone. Check the returned start/end and tell the user what was booked --
the parser guesses, and does not handle attendees or descriptions.

Args:
    text: The phrase to parse, e.g. 'Dentist Thursday 9am' or
        'Team sync every Monday at 10 for 30 minutes'.
    calendar_id: Calendar to create the event on.

Input parameters:

- `calendar_id` (string)
- `text` (string, required)

Output parameters:

- `calendar_id` (string): Calendar the event lives on.
- `event`: The event after the operation.
- `message` (string): One-line human-readable summary of what happened.

### `update_event` (~187 tokens)

Update an event

Change fields on an existing event. Omitted fields are left untouched.

To reschedule while keeping the duration, use `move_event` instead: changing
only `start_time` here leaves the old end time in place.

Args:
    calendar_id: Calendar the event lives on.
    event_id: The event to update (from `find_events`). Required.
    summary: New title.
    start_time: New start, ISO 8601.
    end_time: New end, ISO 8601.
    description: New description.
    location: New location.
    send_notifications: Whether Google emails the attendees. Default true.

Input parameters:

- `calendar_id` (string)
- `description`
- `end_time`
- `event_id` (string)
- `location`
- `send_notifications` (boolean)
- `start_time`
- `summary`

Output parameters:

- `calendar_id` (string): Calendar the event lives on.
- `event`: The event after the operation.
- `message` (string): One-line human-readable summary of what happened.

### `move_event` (~203 tokens)

Move or reschedule an event

Reschedule an event, and/or move it to a different calendar.

Supplying only `new_start` keeps the event's original duration -- this is the
right tool for "push my 2pm back an hour". Supplying
\`destination_calendar_id` transfers the event between calendars.

Args:
    event_id: The event to move (from `find_events`).
    calendar_id: Calendar the event currently lives on.
    new_start: New start, ISO 8601. Duration is preserved if new_end is omitted.
    new_end: New end, ISO 8601. Optional when new_start is given.
    destination_calendar_id: Calendar to transfer the event to.
    send_notifications: Whether Google emails the attendees. Default true.

Input parameters:

- `calendar_id` (string)
- `destination_calendar_id`
- `event_id` (string, required)
- `new_end`
- `new_start`
- `send_notifications` (boolean)

Output parameters:

- `calendar_id` (string): Calendar the event lives on.
- `event`: The event after the operation.
- `message` (string): One-line human-readable summary of what happened.

### `add_attendee` (~115 tokens)

Add attendees

Invite one or more people to an existing event.

Existing attendees are kept; the new addresses are appended.

Args:
    event_id: The event to invite people to (from `find_events`).
    attendee_emails: Email addresses to invite.
    calendar_id: Calendar the event lives on.
    send_notifications: Whether Google emails the attendees. Default true.

Input parameters:

- `attendee_emails` (array, required)
- `calendar_id` (string)
- `event_id` (string, required)
- `send_notifications` (boolean)

Output parameters:

- `calendar_id` (string): Calendar the event lives on.
- `event`: The event after the operation.
- `message` (string): One-line human-readable summary of what happened.

### `respond_to_event` (~152 tokens)

RSVP to an event

Set the user's own RSVP on an invitation they have received.

Only works on events the user is an attendee of; it does not change anyone
else's response.

Args:
    event_id: The invitation to answer (from `find_events`).
    response_status: 'accepted', 'declined', 'tentative' or 'needsAction'.
    calendar_id: Calendar the invitation lives on.
    comment: Optional note sent to the organizer with the RSVP.
    send_notifications: Whether Google emails the organizer. Default true.

Input parameters:

- `calendar_id` (string)
- `comment`
- `event_id` (string, required)
- `response_status` (string, required)
- `send_notifications` (boolean)

Output parameters:

- `calendar_id` (string): Calendar the event lives on.
- `event`: The event after the operation.
- `message` (string): One-line human-readable summary of what happened.

### `schedule_mutual` (~327 tokens)

Find a mutual slot and schedule

Find the first slot where everyone is free, then book the meeting there.

Reads each attendee's free/busy inside the window, picks the earliest gap
that fits `duration_minutes`, and creates the event with all of them invited.
Fails with an error if no common slot exists -- widen the window or shorten
the meeting and try again.

Args:
    attendee_calendar_ids: Attendee email addresses whose availability matters.
    time_min: Earliest the meeting may start, ISO 8601 with a UTC offset.
    time_max: Latest the meeting may end, ISO 8601 with a UTC offset.
    duration_minutes: Length of the meeting in minutes.
    summary: Title for the meeting.
    description: Optional agenda or notes.
    location: Optional location or meeting link.
    organizer_calendar_id: Calendar the meeting is created on.
    working_hours_start: Optional daily earliest start, 'HH:MM' local to the
        calendar, e.g. '09:00'.
    working_hours_end: Optional daily latest end, 'HH:MM', e.g. '17:00'.
    send_notifications: Whether Google emails the attendees. Default true.

Input parameters:

- `attendee_calendar_ids` (array, required)
- `description`
- `duration_minutes` (integer, required)
- `location`
- `organizer_calendar_id` (string)
- `send_notifications` (boolean)
- `summary` (string, required)
- `time_max` (string, required)
- `time_min` (string, required)
- `working_hours_end`
- `working_hours_start`

Output parameters:

- `calendar_id` (string): Calendar the event lives on.
- `event`: The event after the operation.
- `message` (string): One-line human-readable summary of what happened.

### `delete_event` (~118 tokens)

Delete an event

Permanently delete an event. This cannot be undone.

Clients that support elicitation are asked to confirm first; if the user
declines, nothing is deleted and `deleted` comes back false.

Args:
    event_id: The event to delete (from `find_events`).
    calendar_id: Calendar the event lives on.
    send_notifications: Whether Google emails the attendees that it was
        cancelled. Default true.

Input parameters:

- `calendar_id` (string)
- `event_id` (string, required)
- `send_notifications` (boolean)

Output parameters:

- `calendar_id` (string): Calendar the event was on.
- `confirmed_by_user`: True/False when the client answered a confirmation prompt; null when the client does not support elicitation.
- `deleted` (boolean): True when the event was removed.
- `event_id` (string): ID of the deleted event.
- `message` (string): One-line human-readable summary of what happened.

## Diagnostics

Captured diagnostic sections: Provenance, Install scripts, Dependencies. The full working is on the page: https://verifymcp.io/servers/deciduus-calendar-mcp/calendar-mcp-server#diagnostics

## Score history

- 2026-09-21: 72
- 2026-09-20: 72
- 2026-09-19: 71
- 2026-09-18: 71
- 2026-09-17: 70
- 2026-09-16: 70
- 2026-09-15: 69
- 2026-09-14: 69
- 2026-09-13: 68
- 2026-09-12: 65
- 2026-09-11: 65
- 2026-09-10: 65
- 2026-09-09: 65
- 2026-09-08: 65
- 2026-09-07: 65
- 2026-09-06: 65
- 2026-09-05: 50

## Common questions

### What is the io.github.deciduus/calendar-mcp server?

io.github.deciduus/calendar-mcp is listed in the public MCP registry as io.github.deciduus/calendar-mcp. Google Calendar for LLM agents: find, create, update, move, delete events; free/busy; scheduling. This page covers its PyPI package (calendar-mcp-server).

### Is the io.github.deciduus/calendar-mcp server safe to use?

io.github.deciduus/calendar-mcp scores 72 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 21 September 2026. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the io.github.deciduus/calendar-mcp server expose?

io.github.deciduus/calendar-mcp exposes 15 tools: list_calendars, create_calendar, find_events, check_attendee_status, query_free_busy, and 10 more. Their descriptions and schemas cost roughly 2,277 tokens of context every time the server is loaded.

### Is the io.github.deciduus/calendar-mcp server still maintained?

io.github.deciduus/calendar-mcp is still listed as active in the MCP registry. We last reached this channel on 21 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

## Links

- PyPI project: https://pypi.org/project/calendar-mcp-server/
- Socket report: https://socket.dev/pypi/package/calendar-mcp-server
- Repository: https://github.com/deciduus/calendar-mcp
- Changelog RSS feed: https://verifymcp.io/servers/deciduus-calendar-mcp/calendar-mcp-server.xml
- Changelog JSON feed: https://verifymcp.io/servers/deciduus-calendar-mcp/calendar-mcp-server.json
- HTML version of this page: https://verifymcp.io/servers/deciduus-calendar-mcp/calendar-mcp-server