AddCal

Name: AddCal
Author: addcal

by addcalversion 1.0.1i★ –iRuns in the cloud

Registry nameco.addcal/addcal

Install

Overview

Description from the maker (original English)

Publish public calendars and events others subscribe to: RSVPs, feeds and add-to-calendar links.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs in the cloud
Transport: Streamable HTTP
Category: Docs, sheets & office work

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on the maker’s server: what you ask it goes through their server.
The registry lists no key to fill in.

You need

Runs in the cloudNothing to install; it connects over the internet

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Works in Claude on the web, desktop and mobile:

Open Settings → Connectors
Press Add custom connector
Paste the address below and press Add
If it asks you to sign in, sign in with the maker

https://addcal.co/mcp

Run this in your terminal

claude mcp add --transport http addcal https://addcal.co/mcp

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "addcal": {
      "url": "https://addcal.co/mcp"
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "addcal": {
      "type": "http",
      "url": "https://addcal.co/mcp"
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

ChatGPT connects only to servers on the internet:

Open ChatGPT on the web → Settings → Connectors (Apps)
Press Create or Add (some plans need Developer mode under Advanced first)
Paste the address below, give it a name and save
If it asks you to sign in, sign in with the maker

https://addcal.co/mcp

Menu names can differ slightly by plan and over time.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

We have not read this server’s tool list yet; we check endpoints in rotation.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 6, 2026

✓ Pass
Maker matches the repo
The registry name was verified against the domain addcal.co (the registry checks domain ownership)
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
… Not checked yet
Endpoint responds
Not checked yet; we check endpoints in rotation
… Not checked yet
Sign-in with OAuth
Not checked yet; we check endpoints in rotation
… Not checked yet
No hidden instructions in tool descriptions
Not checked yet; we read the tool list when we check the endpoint

Compared with others in Docs, sheets & office worki

More stars than 0% of the other 2169 servers in this category
Published to the registry more recently than 26% of the other 2169 servers in this category
Basic checks equal to or better than 100% of the other 2169 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is AddCal safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.

Is it still maintained?

The GitHub repo last changed –, and the latest version (1.0.1) reached the registry 3 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT in developer mode.

What can I use instead?

In the same category: Agent-Native Calendar, Excel MCP Server, MCP Server for Excel

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Agent-Native Calendar

by BuilderIO

Agent-Native Google Calendar - manage events, sync, and public booking

Runs in the cloud★ 7,620MITUpdated 2 months ago

Install

Excel MCP Server

by haris-musa

Lets AI create and edit Excel files itself, including formulas, charts and PivotTables, without Excel installed.

Runs on your computer★ 4,276MITUpdated 5 days ago

Install

MCP Server for Excel

by sbroenne

Excel automation for AI - Sheets, Power Query, DAX, VBA, Tables, Ranges and more. Windows only.

Runs on your computer★ 847MITUpdated 3 days ago

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

AddCal MCP Server

A remote Model Context Protocol server for AddCal. Connect Claude, ChatGPT, Cursor or any MCP client and manage the calendars other people subscribe to.

https://addcal.co/mcp

No install, no API key. It is a hosted streamable HTTP server and authentication is OAuth.

This is not a Google Calendar MCP

Almost every calendar MCP server does the same job: it reads and writes *your own* schedule. Useful, and well covered already.

AddCal is the other side of the calendar. It manages the events you publish for an audience: a class timetable, a fixture list, a release schedule, a conference programme. The people receiving those events never get an invite. They subscribe to a feed, or they click an add-to-calendar link, and the event lands in whichever calendar app they already use.

That difference shows up in the tools. There is no accept-invite, because nobody is invited. There is list-subscribers, get-analytics and create-calendar-collection, because the questions you ask about a published calendar are how many people follow it and whether anyone actually added the event.

Use a Google Calendar MCP to run your day. Use this one to run a calendar other people follow.

Quick start

Pick your client. Cursor and VS Code install in one click.

Claude Code

claude mcp add --transport http addcal https://addcal.co/mcp

Then run /mcp inside Claude Code to sign in.

Claude Desktop and claude.ai

Settings, Connectors, Add custom connector, then paste https://addcal.co/mcp. Custom connectors need a paid plan.

ChatGPT

Settings, Apps & Connectors, Advanced, turn on Developer mode, then add https://addcal.co/mcp as a connector. Requires a paid plan on the web app.

Anything else

Any client that speaks streamable HTTP with OAuth. Windsurf, Goose, Zed and the JetBrains AI Assistant all take a remote MCP URL.

"mcpServers": { "addcal": { "type": "http", "url": "https://addcal.co/mcp" } } }

Authentication

OAuth 2.1 with PKCE and dynamic client registration. There is no API key to copy and paste.

Your client registers itself, you approve it in a browser, and it receives a token scoped to your team. It can reach exactly what you can reach, no more. Revoke any connected client from Settings, API.

What you can ask for

What have I got on next week?

Create a team standup every weekday at 9am and show me the dates first. Who has RSVPed yes to the launch party? Duplicate last month's workshop into March. Which of my events got the most add-to-calendar clicks?

Tools

19 tools. RO is read only. Required parameters are marked *.

Search

Tool		Parameters
`search`	RO	`query*`, `limit`, `team_id`

One call across calendars, collections, events and RSVPs, returning the ids every other tool needs. Start here whenever something is named rather than identified.

Calendars

Tool		Parameters
`list-calendars`	RO	`search`, `limit`, `team_id`
`create-calendar`		`name*`, `description`, `timezone`, `team_id`

Collections

A collection bundles several calendars behind one public page and subscribe link.

Tool		Parameters
`list-calendar-collections`	RO	`team_id`
`create-calendar-collection`		`name`, `calendar_ids`, `description`, `allow_subscriber_selection`, `team_id`

Subscribers

Tool		Parameters
`list-subscribers`	RO	`calendar_id*`, `status`, `search`, `limit`

Returns personal data. Names and emails exist only for calendars that ask subscribers for details, so many rows are anonymous.

Events

Tool		Parameters
`list-events`	RO	`calendar_id`, `search`, `range`, `start_date`, `end_date`, `limit`, `team_id`
`get-event`	RO	`event_id*`
`create-event`		`calendar_id`, `title`, `date_start`, `date_end`, `timezone`, `description`, `location`, `is_all_day`, `is_draft`, `has_rsvp`, `recurrence_rule`, `series_title`, `reminder_before`
`update-event`		`event_id*`, `title`, `description`, `location`, `date_start`, `date_end`, `timezone`, `is_all_day`, `is_draft`, `has_rsvp`, `recurrence_rule`, `reminder_before`
`duplicate-event`		`event_id*`, `target_calendar_id`, `title`, `date_start`, `date_end`
`delete-event`	destructive	`event_id`, `confirm`, `notify_invitees`
`preview-recurring-dates`	RO	`recurrence_rule`, `date_start`, `date_end*`, `timezone`, `is_all_day`, `count`

Recurrence uses RFC 5545 rules without the RRULE: prefix, such as FREQ=WEEKLY;BYDAY=MO;COUNT=10. Run preview-recurring-dates before creating a series to check the dates land where you expect.

RSVPs

Tool		Parameters
`list-rsvps`	RO	`event_id*`, `response_type`, `search`, `limit`
`create-rsvp`	destructive	`event_id`, `name`, `email`, `response_type`, `confirm*`, `custom_fields`, `send_confirmation`

create-rsvp emails the attendee by default. Set send_confirmation to false to record an RSVP silently.

Invites

Tool		Parameters
`list-invites`	RO	`event_id*`, `status`, `search`, `limit`
`send-event-invite`	destructive	`event_id`, `email`, `confirm*`

Account

Tool		Parameters
`get-analytics`	RO	`calendar_id`, `event_id`, `start_date`, `end_date`, `timezone`, `unique_only`, `include_series`, `team_id`
`get-team-usage`	RO	`team_id`

Destructive tools

Three tools are annotated destructive, and all three require an explicit confirm parameter:

send-event-invite and create-rsvp email a real person. That cannot be recalled.
delete-event is permanent, and deleting a recurring event removes every instance in the series.

A well-behaved client surfaces these for approval before running them. Check the name and address when your assistant asks.

Plans and limits

The server is included on every plan, and the tools respect whatever your plan already allows. Collections, calendar invites and analytics stay gated to the plans that include them. When a tool hits a limit it explains why rather than retrying.

About this repository

AddCal's MCP server is hosted, so there is nothing here to install or run. This repository holds the published server.json manifest and the documentation for the remote endpoint. The implementation lives in the main AddCal application.

Found a problem with a tool, or want one that does not exist yet? Open an issue.

AddCal

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Docs, sheets & office worki

Common questions

Alternatives

Agent-Native Calendar

Excel MCP Server

MCP Server for Excel

README from the maker

AddCal MCP Server

This is not a Google Calendar MCP

Quick start

Authentication

What you can ask for

Tools

Search

Calendars

Collections

Subscribers

Events

RSVPs

Invites

Account

Destructive tools

Plans and limits

Links

About this repository