GA4 Measurement Plan
Give it a site URL and get back a complete GA4 measurement plan — which events to track, what parameters each carries, which custom dimensions to register, and which events to mark as key events. The deliverable is a spec a developer or GTM builder can implement directly. No account connection required.
It pairs with /gtm-tracking-plan, which turns this plan into the actual GTM tags,
triggers, and variables.
Works with
Works with zero accounts (site URL only). When connected, the plan becomes a gap list against what is already live instead of a blank-slate spec:
| Job | Without accounts | Enhanced when connected |
|---|---|---|
| What's already tracked | inferred from the site | GA4 tool_get_metadata, tool_run_report (eventName); Segment list_tracking_plan_rules; PostHog list_event_definitions |
| Key events already marked | — | GA4 tool_list_conversion_events |
| Dimensions already registered | — | GA4 tool_list_custom_dimensions |
| Mark the planned key events | user does it in GA4 Admin | GA4 tool_mark_key_event if exposed (write, asks first), else GA4 Admin |
Usage
/ga4-measurement-plan example.com — measurement plan for the site
/ga4-measurement-plan example.com "drive demo bookings" — bias the plan toward a goal
Steps
1. Understand the site
WebFetch the URL and a representative spread of pages (home, product/category,
pricing, signup/checkout, contact). Determine:
- Site type — ecommerce, lead gen, SaaS, content/media, marketplace
- The primary conversion and any secondary conversions (newsletter, demo, account creation)
- The funnel steps a visitor passes through to convert
- Notable interactions worth measuring (search, filters, video, downloads, configs)
If a business goal was passed as an argument, make the plan serve it first.
1b. Inventory what's live (enhanced when connected)
If Cogny isn't connected, skip this and note what connecting adds.
Call list_integrations once and use whichever of these are healthy:
| Provider | Calls | Gives you |
|---|---|---|
| GA4 | tool_list_account_summaries → tool_run_report (property_id, last 30 days, dimensions: [eventName], metrics: [eventCount]), tool_list_conversion_events, tool_list_custom_dimensions, tool_get_metadata | Events firing, key events, registered parameters |
| Segment | list_tracking_plans → list_tracking_plan_rules (tracking_plan_id) | The team's existing event names and required properties |
| PostHog | list_projects → list_event_definitions (project_id) | Product events already named (often the source of truth for SaaS) |
| Mixpanel | run_segmentation (event, from_date, to_date) per candidate event | Whether a product event already fires |
Add a Status column to the Step 5 table: live / live, rename / new. Reuse the
existing product-analytics name in a parameter when it differs from the GA4 name, so the
same action is joinable across tools.
2. Start from what GA4 already gives you
Note which events come free and need no implementation:
- Automatically collected:
first_visit,session_start,page_view,user_engagement - Enhanced Measurement (if enabled):
scroll,click(outbound),view_search_results,video_*,file_download,form_start,form_submit
Flag any of these the team should rely on rather than rebuild.
3. Recommended events for the site type
Map the site to GA4's recommended events — using the recommended names matters because GA4 builds reporting around them:
- Ecommerce:
view_item_list,view_item,select_item,add_to_cart,view_cart,begin_checkout,add_shipping_info,add_payment_info,purchase,refund - Lead gen / SaaS:
generate_lead,sign_up,login,search, plus custom events for the funnel - Content / media:
search,select_content,share,join_group
For each: when it fires and its parameters (e.g. purchase → transaction_id,
value, currency, items[]).
4. Custom events for everything else
For interactions GA4 has no recommended event for, design custom events following the
rules: snake_case, ≤40 characters, descriptive, no reserved prefixes
(google_, firebase_, ga_), lowercase. Examples: demo_requested,
pricing_plan_selected, quote_calculated.
Keep the taxonomy tight — a parameter on a shared event usually beats a brand-new
event (cta_click with a cta_location parameter, not ten separate click events).
5. The event taxonomy table
Produce the core deliverable — one row per event:
| Event name | Type | Fires when | Parameters | Key event? |
|---|---|---|---|---|
purchase | recommended | order confirmation page loads | transaction_id, value, currency, items[] | ✅ |
generate_lead | recommended | contact form submitted | form_id, lead_source, value | ✅ |
demo_requested | custom | demo form submitted | plan_interest | ✅ |
| ... |
6. Custom dimensions & metrics to register
Event parameters are invisible in standard GA4 reports until registered as custom dimensions. List every non-standard parameter from Step 5 that needs registering:
| Parameter | Scope | Register as | Why |
|---|---|---|---|
lead_source | event | custom dimension | segment leads by origin |
plan_interest | event | custom dimension | see which plan drives demos |
Warn against high-cardinality parameters (IDs, timestamps) as dimensions, and note the 50 event-scoped / 25 user-scoped limits.
7. Key events (conversions)
Recommend which events to mark as key events. Be selective — 3–8 is healthy. Mark
real business outcomes, never page_view or scroll. Note which key events should
also be imported into Google Ads for bidding.
If GA4 is connected and the workspace exposes tool_mark_key_event (it's newer than most
workspaces' tool lists), offer to mark the agreed key events with it (property_id, event_name;
write, asks first, once per event). Otherwise give the GA4 UI path: Admin → Events → Mark as key
event. Either way it only works for events that already fire, and counts new data only.
8. Output
Deliver as one document:
GA4 Measurement Plan — [site] Site type: ... | Primary conversion: ... 1. Already covered (automatic + Enhanced Measurement): ... 2. Event taxonomy table (recommended + custom) 3. Custom dimensions & metrics to register 4. Key events to mark as conversions (and which to send to Google Ads) 5. dataLayer payload examples for the 3-5 most important events 6. Implementation notes & sequencing
End with the handoff line: "Run /gtm-tracking-plan [url] to turn this into GTM
tags, triggers, and variables."
Critical rules
- Use GA4's recommended event names wherever one exists — reporting depends on them.
- A registered parameter beats a new event. Keep the taxonomy small.
- Custom events must follow the naming rules —
snake_case, ≤40 chars, no reserved prefixes. - Never recommend collecting PII (email, phone, name) in events or parameters — it violates Google policy.
- Connected data adds status, not scope. Don't drop a needed event because it isn't
live yet; mark it
new. - This produces a plan. To audit a live GA4 property, use
/ga4-audit(requires Cogny MCP).
