Using Vertex AI in Firebase requires that your Firebase project use the pay-as-you-go (Blaze) pricing plan.
Find the pricing for each model in the Google Cloud documentation.
You can also get an estimate of the token size and billable characters of your requests using the Count Tokens API. Learn more about token limits per model and pricing per model.
To avoid surprise bills, make sure that you monitor your costs and usage and set up budget alerts.