io.usefulapi/addevent

What it mainly works on, as our AI model read its tool descriptions: accounts and data in outside web services.

6 of 18 tools are described as changing something (creating, editing, deleting, sending or running).

• addevent_list_calendarsreads or searches

  “List the account's calendars (newest first by default) with id, title, timezone, whether it is the default calendar, landing-page links and counts of events and subscribers.”

  Publisher declares: read-only yes · destructive no · open-world yes

  5 inputs

  • calendar_idsarray“Only these calendar ids.”
  • sort_bystring“Sort field (default created).”
  • sort_orderstring“Sort direction.”
  • pageinteger“Page number, from 1 (default 1).”
  • page_sizeinteger“Results per page, 1-20 (default 10).”
• addevent_get_calendarreads or searches

  “One calendar by id: title, timezone, week start, template ids, subscriber and event counts, links, custom data.”

  Publisher declares: read-only yes · destructive no · open-world yes

  1 input, 1 required

  • calendar_idstring or integerrequired“Calendar id (see addevent_list_calendars).”
• addevent_create_calendarcreates or changes datadescribed as changing data

  “WRITE: creates a new calendar in the AddEvent account (a new, empty calendar; nothing existing is changed and nobody is notified).”

  Publisher declares: read-only no · destructive no · idempotent no · open-world yes

  9 inputs, 1 required

  • titlestringrequired“Calendar title (single line).”
  • timezonestring“Default timezone for events on this calendar (IANA name).”
  • weekday_beginstring“First day of the week.”
  • descriptionstring“Shown on the calendar landing page.”
  • internal_namestring“Internal name, never shown publicly.”
  • calendar_colorinteger“Color 1-20 from the palette.”
  • landing_page_template_idstring“Calendar landing page template id, or 'default' (see addevent_list_calendar_templates).”
  • embeddable_calendar_template_idstring“Embeddable calendar template id, or 'default'.”
  • custom_dataobject“Arbitrary key-value pairs to store on the object (snake_case keys), e.g.”
• addevent_update_calendarcreates or changes datadescribed as changing data

  “WRITE: changes fields of an existing calendar (only the fields you pass; the rest stay).”

  Publisher declares: read-only no · destructive yes · idempotent yes · open-world yes

  10 inputs, 1 required

  • calendar_idstring or integerrequired“Calendar id to change.”
  • titlestring“New title (single line).”
  • timezonestring“IANA timezone such as America/Los_Angeles, or 'floating' (same local time for everyone).”
  • weekday_beginstring
  • descriptionstring
  • internal_namestring“Internal name, never shown publicly.”
  • calendar_colorinteger“Color 1-20 from the palette.”
  • landing_page_template_idstring
  • embeddable_calendar_template_idstring
  • custom_dataobject“Key-value pairs to store on the calendar (snake_case keys).”
• addevent_list_eventsreads or searches

  “Search the account's events (newest created first; by start time when a date filter is used): title, start/end, timezone, location, RSVP settings and stats, landing-page links.”

  Publisher declares: read-only yes · destructive no · open-world yes

  11 inputs

  • calendar_idsarray“Only events on these calendar ids.”
  • event_idsarray“Only these event ids.”
  • starts_beforestring“Only events that start before this date-time (datetime_max; naive comparison, timezones ignored).”
  • ends_afterstring“Only events that end after this date-time (datetime_min; naive comparison, timezones ignored).”
  • searchstring“Case-insensitive text in title, internal name, description or location.”
  • custom_data_keystring“Custom data key (needs custom_data_value).”
  • custom_data_valuestring“Custom data value (needs custom_data_key).”
  • sort_bystring“Sort field.”
  • sort_orderstring“Sort direction.”
  • pageinteger“Page number, from 1 (default 1).”
  • page_sizeinteger“Results per page, 1-20 (default 10).”
• addevent_get_eventreads or searches

  “One event by id (evt-...): all fields incl.”

  Publisher declares: read-only yes · destructive no · open-world yes

  1 input, 1 required

  • event_idstring or integerrequired“Event id, like evt-0f571af553d8437eb6a9ce22384fdcba (see addevent_list_events).”
• addevent_create_eventcreates or changes datadescribed as changing data

  “WRITE: creates a new event on a calendar (the account's default calendar if calendar_id is omitted).”

  Publisher declares: read-only no · destructive no · idempotent no · open-world yes

  20 inputs, 2 required

  • titlestringrequired“Event title (single line).”
  • datetime_startstringrequired“Start date-time: YYYY-MM-DD, YYYY-MM-DD hh:mm or YYYY-MM-DD hh:mm:ss.”
  • calendar_idstring or integer“Calendar to add the event to (see addevent_list_calendars); default calendar if omitted.”
  • datetime_endstring“End date-time (default: start + 1 hour).”
  • all_day_eventboolean“All-day event: only the dates are used.”
  • timezonestring“IANA timezone for the start/end (default: the calendar's timezone), or 'floating'.”
  • recurring_rulestring“iCalendar recurrence rule such as FREQ=WEEKLY;COUNT=10.”
  • descriptionstring“Plain text or simple HTML (keep under ~500 characters for cross-browser links).”
  • internal_namestring“Internal name, never shown publicly.”
  • locationstring“Address or URL (meeting link).”
  • location_idinteger“Id of a saved location (0 = none).”
  • organizer_namestring“Organizer name (needs organizer_email).”
  • organizer_emailstring“Organizer e-mail (needs organizer_name).”
  • reminderinteger“Minutes before the start for a calendar-app reminder (0-10800).”
  • colorinteger“Color 1-20 from the palette.”
  • free_busystring“How the event shows in an attendee's calendar.”
  • landing_page_template_idstring“Event landing page template id or 'default' (see addevent_list_event_templates).”
  • rsvp_enabledboolean“Require an RSVP before the event can be added to a calendar.”
  • rsvp_form_idstring“RSVP form id or 'default' (see addevent_list_rsvp_forms).”
  • custom_dataobject“Arbitrary key-value pairs to store on the object (snake_case keys), e.g.”
• addevent_update_eventcreates or changes datadescribed as changing data

  “WRITE: changes fields of an existing event (only the fields you pass; the rest stay).”

  Publisher declares: read-only no · destructive yes · idempotent yes · open-world yes

  21 inputs, 1 required

  • event_idstring or integerrequired“Event id (evt-...) to change.”
  • titlestring“New title (single line).”
  • datetime_startstring“New start: YYYY-MM-DD, YYYY-MM-DD hh:mm or YYYY-MM-DD hh:mm:ss.”
  • calendar_idstring or integer“Move the event to this calendar id.”
  • datetime_endstring“End date-time (default: start + 1 hour).”
  • all_day_eventboolean“All-day event: only the dates are used.”
  • timezonestring“IANA timezone for the start/end (default: the calendar's timezone), or 'floating'.”
  • recurring_rulestring“iCalendar recurrence rule such as FREQ=WEEKLY;COUNT=10.”
  • descriptionstring“Plain text or simple HTML (keep under ~500 characters for cross-browser links).”
  • internal_namestring“Internal name, never shown publicly.”
  • locationstring“Address or URL (meeting link).”
  • location_idinteger“Id of a saved location (0 = none).”
  • organizer_namestring“Organizer name (needs organizer_email).”
  • organizer_emailstring“Organizer e-mail (needs organizer_name).”
  • reminderinteger“Minutes before the start for a calendar-app reminder (0-10800).”
  • colorinteger“Color 1-20 from the palette.”
  • free_busystring“How the event shows in an attendee's calendar.”
  • landing_page_template_idstring“Event landing page template id or 'default' (see addevent_list_event_templates).”
  • rsvp_enabledboolean“Require an RSVP before the event can be added to a calendar.”
  • rsvp_form_idstring“RSVP form id or 'default' (see addevent_list_rsvp_forms).”
  • custom_dataobject“Arbitrary key-value pairs to store on the object (snake_case keys), e.g.”
• addevent_list_rsvp_attendeesreads or searches

  “List RSVP attendees (personal data: e-mail addresses and the answers they gave on the RSVP form).”

  Publisher declares: read-only yes · destructive no · open-world yes

  7 inputs

  • event_idsarray“Only attendees of these event ids.”
  • calendar_idsarray“Only attendees of events on these calendar ids.”
  • attendingstring“Only attendees with this response.”
  • sort_bystring
  • sort_orderstring“Sort direction.”
  • pageinteger“Page number, from 1 (default 1).”
  • page_sizeinteger“Results per page, 1-20 (default 10).”
• addevent_get_rsvp_attendeereads or searches

  “One RSVP attendee by id (personal data: e-mail and form answers; IP address and coordinates removed).”

  Publisher declares: read-only yes · destructive no · open-world yes

  1 input, 1 required

  • attendee_idstring or integerrequired“RSVP attendee id (see addevent_list_rsvp_attendees).”
• addevent_create_rsvp_attendeecreates or changes datadescribed as changing data

  “WRITE: adds ONE RSVP attendee (one e-mail address, personal data) to an event.”

  Publisher declares: read-only no · destructive no · idempotent no · open-world yes

  4 inputs, 2 required

  • event_idstring or integerrequired“Event id (evt-...) to RSVP to.”
  • emailstringrequired“Attendee e-mail address (unique per event).”
  • attendingstring“The attendee's response.”
  • rsvp_form_dataobject“Answers to the event's RSVP form as field-name -> value.”
• addevent_update_rsvp_attendeecreates or changes datadescribed as changing data

  “WRITE: changes ONE RSVP attendee (email, response or form answers; only the fields you pass).”

  Publisher declares: read-only no · destructive yes · idempotent yes · open-world yes

  4 inputs, 1 required

  • attendee_idstring or integerrequired“RSVP attendee id.”
  • emailstring“New e-mail address.”
  • attendingstring
  • rsvp_form_dataobject“Answers to the event's RSVP form as field-name -> value.”

Each quoted sentence is the first sentence of the publisher’s own description. The kind of tool and the “changes data” mark are our AI model’s reading of that description, not something we tested: two differently worded runs had to agree, otherwise no label is shown, and nobody has checked them by hand. A tool without the “changes data” mark is described as only reading, searching or calculating, or the two runs did not agree. No tool was called. Read the publisher’s full description before relying on it. “Publisher declares” lists the hints the server itself sends with the tool (MCP annotations: read-only, destructive, idempotent, open-world); they are the publisher's claims, not checked by us. Inputs are the parameters in the tool's own input schema: name, declared type, whether it is required, and the first sentence of its description. Read 2026-10-23.

The registry verifies a package once, when it is published, and does not re-check it. A difference below is about the listing, not a judgement of the publisher.