Google Cloud's App Topology API Billing Starts October 15

App Topology API billing begins on October 15, 2026, one week from today. From that date, Google meters the API that draws the agent and MCP server graphs in Gemini Enterprise Agent Platform, Cloud Hub and Cloud Monitoring. Each project gets a daily free allotment, and everything above it costs money. If a team of yours opens those graphs, someone should own the bill before the 15th.

App Topology API billing: what changes on October 15

The Gemini Enterprise Agent Platform release notes say the App Topology API reached general availability on September 30, 2026. Two weeks later it starts costing money. The App Topology documentation gives the rates:

| Meter | Free per project, per day | Price beyond that | | --- | --- | --- | | Queries | 100 | $0.01 per query | | Nodes in topology graphs | 15,000 | $0.00075 per node |

Billing covers all App Topology API usage, whichever product draws the graph. A node is a discovered Google Cloud resource or a resource registered in an App Hub application: a VM, an agent, an alert, a vulnerability.

A date discrepancy to know about

Not every Google page agrees. The App Topology overview page and an August 10 Cloud Hub release note still say September 15. The Hub documentation, the agent topology page and the Cloud Monitoring topology page all say October 15, and the Hub page was updated most recently. I found no postponement notice, so plan for October 15 and confirm the meter in your Billing console.

Who pays: teams using agent topology

If your project stays under 100 queries and 15,000 nodes a day, nothing changes. Projects with many registered agents and MCP servers, or with people refreshing topology pages all day, are the ones to watch. The docs don't define exactly what counts as one query or one node, so you can't predict spend from page views alone.

Here is my own arithmetic using the published rates, assuming both meters bill independently. A project that runs 500 queries and returns 100,000 nodes a day pays (500 - 100) x $0.01 = $4.00 for queries and (100,000 - 15,000) x $0.00075 = $63.75 for nodes. That is $67.75 a day, about $2,030 over 30 days. The node meter dominates.

Which agents appear in agent topology

Eligibility decides how big your graphs get:

• Agents must have the functional type AGENT and be deployed with ADK, Gemini Enterprise or Cloud Run. Agents on GKE must be registered with Agent Registry.
• MCP servers must have the functional type MCP. First-party servers on OneMCP, GKE or Cloud Run are included. Other MCP servers must be registered with Agent Registry.
• Tools, models and Workspace Agents are not included.

Registered MCP servers show up without edges, because App Hub treats them as a shared resource.

Set an alert and a cap before October 15

First, find which projects have apptopology.googleapis.com enabled.

gcloud services list --enabled \
  --project=<your-project-id> \
  --filter="config.name:apptopology.googleapis.com"

This prints a row if the API is on; loop it over your project list.

Next, create a budget alert. Google's budgets documentation is explicit that an alerts-only budget doesn't cap usage or spending, so treat this as an early warning.

gcloud billing budgets create \
  --billing-account=<your-billing-account-id> \
  --display-name="App Topology watch" \
  --budget-amount=200USD \
  --calendar-period=month \
  --filter-projects=projects/<your-project-id> \
  --threshold-rule=percent=0.5 \
  --threshold-rule=percent=0.9,basis=forecasted-spend

This budget covers all spend in the project. To scope it to App Topology, add --filter-services=services/<service-id>, using the ID from the Cloud Billing Catalog API.

Finally, for a sandbox project where nobody needs graphs, a hard stop is to turn the API off:

gcloud services disable apptopology.googleapis.com \
  --project=<your-sandbox-project-id>

Expect the topology views in the products above to stop working there. I found no documented per-day quota for this API, so check its quota page in the console before relying on one.

What to do on Monday morning

1. List the projects with App Topology enabled and name an owner for each.
2. Create the budget alerts above for the busy ones.
3. Ask platform teams who actually opens topology pages, and whether any dashboard or script polls the API.
4. After October 15, read a week of real billing data and replace guesses with a number.

Agent observability used to be a free feature, and now it is a line item, so someone has to own it before the first invoice arrives.