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Google Cloud's fully managed platform for building, deploying, and discovering AI agents — the closest thing to an enterprise agent PaaS.
Why It Matters
Vertex AI Agent Builder is Google's bet on making agent development as managed as App Engine made web development. The Agent Development Kit (ADK) has 7M+ downloads across Python, Java, and Go, with one-command deployment (adk deploy) to Agent Engine runtime. Agent Garden (preview) provides a curated library of Google-authored sample agents. The platform includes Model Armor for prompt injection defense, Cloud API Registry for tool governance, and A2A protocol support. Free tier available for Agent Engine Runtime.
Strengths
- Fully managed: build, deploy, evaluate, and monitor agents without managing infrastructure
- Pre-built agent templates and extensions accelerate development
- Native integration with Google Cloud data services (BigQuery, Cloud Storage, Vertex AI Search)
- Built-in agent evaluation framework for testing and quality assurance
- A2A support enables interoperability with agents outside Google's ecosystem
Limitations
- Deep Google Cloud lock-in — agents built here don't port to AWS or Azure
- Pricing is complex and tied to Google Cloud usage, making cost prediction difficult
- Primarily Gemini-optimized; using non-Google models requires additional configuration
- The "builder" is more managed service than marketplace — limited third-party agent discovery
Risks
- There is no Google agent marketplace — Agent Garden is a handful of Google-authored sample agents, not a registry
- No third-party publishing to Agent Garden; calling it a "marketplace component" would be generous
- Sessions, Memory Bank, and Code Execution started charging Feb 2026 — costs add up quickly beyond the free tier
- Google's track record of killing products makes long-term commitment risky for any team not already all-in on Google Cloud
- The Gemini Enterprise agent publishing feature is just internal app distribution within a GCP tenant, not a real marketplace