/ga4-events

name: ga4-events
description: GA4 Event Implementation Reference — complete event taxonomy, parameter lists, implementation patterns (gtag.js, GTM, Measurement Protocol), and validation techniques
version: "1.0.0"
author: Cogny AI
platforms: []
user-invocable: true
argument-hint: "<event name, category, or topic>"
allowed-tools:
  - WebFetch
  - WebSearch
  - Bash
  - Read
  - Write
  # GA4 tools (when connected via Cogny MCP)
  - mcp__cogny__google_analytics_4__tool_list_account_summaries
  - mcp__cogny__google_analytics_4__tool_get_property
  - mcp__cogny__google_analytics_4__tool_list_custom_dimensions
  - mcp__cogny__google_analytics_4__tool_list_custom_metrics
  - mcp__cogny__google_analytics_4__tool_list_conversion_events
  - mcp__cogny__google_analytics_4__tool_list_data_streams
  - mcp__cogny__google_analytics_4__tool_get_metadata
  - mcp__cogny__google_analytics_4__tool_run_report
  - mcp__cogny__google_analytics_4__tool_run_realtime_report

GA4 Event Implementation Reference

Complete reference for implementing Google Analytics 4 events: automatically collected, enhanced measurement, recommended, and custom events with exact parameter lists, code examples, and validation techniques.

Full docs: https://cogny.com/docs/ga4-event-implementation

Usage

/ga4-events                          # Show event model overview
/ga4-events purchase                 # Show purchase event parameters and code
/ga4-events ecommerce                # Full e-commerce event funnel reference
/ga4-events enhanced measurement     # Enhanced measurement events list
/ga4-events custom events            # Custom event naming rules and limits
/ga4-events validation               # DebugView, Realtime, and BigQuery checks
/ga4-events gtm                      # GTM dataLayer implementation patterns
/ga4-events measurement protocol     # Server-side Measurement Protocol examples

Instructions

You are a GA4 event implementation expert. Use this reference to help users implement, audit, and validate GA4 events correctly. Provide precise, copy-paste-ready code examples.

When the user asks a question, find the relevant section below and provide actionable answers with ready-to-use code. If GA4 MCP tools are available, use them to inspect the user's actual property configuration (custom dimensions, data streams, conversion events) for context-aware advice.

If the user provides a specific event name or topic as an argument, focus on that area. Otherwise, provide an overview of the event model.

---

Event Model Overview

GA4 uses an event-based data model where **everything is an event**. Unlike Universal Analytics hit types (pageview, event, transaction), GA4 has a single concept: events with parameters.

| Concept | Universal Analytics | GA4 | |---------|-------------------|-----| | Data model | Hit-based (pageview, event, transaction) | Event-based (everything is an event) | | Event structure | Category / Action / Label / Value | Event name + parameters (key-value pairs) | | Sessions | Server-defined, 30-min timeout | Derived from `session_start` event | | Pageviews | Dedicated hit type | `page_view` event with `page_location` parameter | | E-commerce | Enhanced Ecommerce plugin | Built-in recommended events with items array | | Custom data | Custom dimensions/metrics (index-based) | Event parameters + custom dimensions/metrics (name-based) |

Every GA4 event has:

• **Event name**: String identifier (e.g., `page_view`, `purchase`)
• **Event parameters**: Key-value pairs (e.g., `page_location`, `transaction_id`)
• **User properties**: Persistent user attributes (e.g., `membership_tier`)

Automatically Collected Events

Collected automatically with no configuration. Cannot be disabled.

Web

| Event | Trigger | Key Parameters | |-------|---------|----------------| | `first_visit` | First time user visits (new cookie) | None | | `session_start` | New session begins (30-min timeout) | `ga_session_id`, `ga_session_number` | | `page_view` | Every page load (or `history.pushState` in SPAs) | `page_location`, `page_title`, `page_referrer` | | `user_engagement` | Page in focus for 1+ second with interaction | `engagement_time_msec` |

Mobile (Firebase SDK)

| Event | Trigger | Key Parameters | |-------|---------|----------------| | `first_open` | First app open after install | `previous_gmp_app_id`, `updated_with_analytics` | | `session_start` | New session begins | `ga_session_id`, `ga_session_number` | | `screen_view` | Screen transition | `firebase_screen`, `firebase_screen_class`, `firebase_screen_id` | | `user_engagement` | App in foreground 1+ second | `engagement_time_msec` | | `app_update` | App updated and launched | `previous_app_version` | | `app_remove` | App removed (Android only) | None | | `os_update` | OS updated | `previous_os_version` |

Auto-attached Parameters (every event)

`language`, `page_location`, `page_referrer`, `page_title`, `screen_resolution`, `ga_session_id`, `ga_session_number`, `engagement_time_msec`

Enhanced Measurement Events

Collected automatically when enabled in **Admin > Data Streams > Enhanced Measurement**. Each can be toggled individually.

| Event | Trigger | Key Parameters | |-------|---------|----------------| | `scroll` | User scrolls past 90% of page | `percent_scrolled` (always 90) | | `click` | Outbound link click | `link_url`, `link_domain`, `link_classes`, `link_id`, `outbound` | | `view_search_results` | URL contains search query parameter | `search_term` | | `video_start` | YouTube embed starts playing | `video_url`, `video_title`, `video_provider`, `video_current_time`, `visible` | | `video_progress` | YouTube video reaches 10/25/50/75% | Same as `video_start` plus `video_percent` | | `video_complete` | YouTube video reaches end | Same as `video_start` | | `file_download` | Click on file link (pdf, xls, doc, zip, etc.) | `file_name`, `file_extension`, `link_url`, `link_text`, `link_domain` | | `form_start` | First inter