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AI-assisted summary of Google's Agentic AI Stack: Gemini, ADK, A2A With Google Cloud — original source. Check the original for full context.
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## Background Published on YouTube by the Ai4 channel on August 28, 2025, this presentation features Dave Elliott, Head of Developer Advocacy for AI at Google Cloud. According to the description, the session explores the core components of an agentic stack—orchestration, models, and tools—and unveils Google Cloud's architecture, including the Agent Development Kit (ADK), Model Context Protocol (MCP), and Agent2Agent (A2A) protocol.
## TL;DR Dave Elliott details the architectural evolution of generative AI from basic prompts to collaborative multi-agent swarms, outlining the key roadblocks in moving agents into enterprise production. He unveils Google Cloud's four-pillar agentic stack, comprising the open-source Agent Development Kit (ADK), Model Context Protocol (MCP) integration, the managed Vertex AI Agent Engine runtime, and the Linux Foundation-governed Agent2Agent (A2A) protocol. The session highlights ADK's code-first, model-agnostic design, flexible containerized deployment options across Cloud Run and Kubernetes, and native multimodal streaming capabilities. Elliott concludes with concrete getting-started steps via the `google-adk` and `a2a-sdk` Python packages alongside runnable sample repositories.
## Atmosphere & style The presentation carries a brisk, engaging, and pragmatic conference energy, opening with self-deprecating humor about being the only speaker standing between the audience and the evening cocktail hour. Elliott maintains a swift, articulate pace, grounding ambitious AI concepts in practical software engineering terminology, clean architectural diagrams, and direct developer workflows rather than vague industry hype. The mood is approachable and encouraging, wrapping up on an inviting, community-oriented note that urges attendees to experiment with the open-source toolkits and visit the conference booth.
## Key takeaways - [00:04](https://www.youtube.com/watch?v=72zGRb3CpFw&t=4s) AI agents represent the primary vehicle through which enterprises and developers will unlock the tangible value and promise of large language models. - [00:04](https://www.youtube.com/watch?v=72zGRb3CpFw&t=4s) Early enterprise agent adoption stalled due to ecosystem fragmentation, rapidly shifting models, lack of MLOps lifecycle management, and missing governance. - [02:52](https://www.youtube.com/watch?v=72zGRb3CpFw&t=172s) Generative AI has evolved across five stages: raw prompt-response, RAG grounding, function calling, reasoning loops with tools, and decentralized multi-agent collaboration. - [02:52](https://www.youtube.com/watch?v=72zGRb3CpFw&t=172s) Every agentic architecture fundamentally relies on a core triad: orchestration (workflow control), models (reasoning), and tools/APIs (data and actions). - [05:20](https://www.youtube.com/watch?v=72zGRb3CpFw&t=320s) Google Cloud's agentic stack consists of four components (ADK, MCP, Vertex AI Agent Engine, and A2A), three of which are open source or open protocols to prevent vendor lock-in. - [07:14](https://www.youtube.com/watch?v=72zGRb3CpFw&t=434s) The Agent Development Kit (ADK) is an open-source, code-first client framework built specifically by software developers for software developers without restrictive black-box abstractions. - [07:14](https://www.youtube.com/watch?v=72zGRb3CpFw&t=434s) ADK is designed to be model-agnostic and deployment-agnostic, supporting non-Google models and running across Vertex AI, Cloud Run, GKE, or self-hosted on-prem environments. - [07:14](https://www.youtube.com/watch?v=72zGRb3CpFw&t=434s) Key ADK capabilities include native multimodal bidirectional streaming, integrated evaluation suites, and support for both deterministic workflows and dynamic reasoning loops. - [09:47](https://www.youtube.com/watch?v=72zGRb3CpFw&t=587s) The Model Context Protocol (MCP) functions complementarily with ADK, enabling agents to seamlessly consume external MCP servers as tools or expose internal ADK tools via MCP. - [11:34](https://www.youtube.com/watch?v=72zGRb3CpFw&t=694s) Vertex AI Agent Engine acts as the managed enterprise runtime, handling operational burdens like short- and long-term memory management, tracing, security, and sandboxed execution. - [12:19](https://www.youtube.com/watch?v=72zGRb3CpFw&t=739s) The Agent2Agent (A2A) protocol, contributed to the Linux Foundation, standardizes multi-agent collaboration through Agent Cards, task dispatching, and asynchronous push notifications. - [14:06](https://www.youtube.com/watch?v=72zGRb3CpFw&t=846s) Developers can begin building and experimenting with the ecosystem immediately using the `google-adk` and `a2a-sdk` Python packages alongside official reference implementations.
## Detailed walkthrough ### [00:04](https://www.youtube.com/watch?v=72zGRb3CpFw&t=4s) Unlocking LLM Value and the Challenges of the Agentic Landscape
Opening with a lighthearted joke about being the only barrier between the audience and the conference happy hour ("I'm the last one standing between you and the cocktail hour. Uh, so I plan to take three hours. No. Okay."), Dave Elliott introduces himself as a 13-year Google veteran leading the developer evangelism and engineering team. With roughly eighteen minutes on the clock, his goal is not to deliver an exhaustive deep dive, but rather to outline Google's Agentic AI stack, provide foundational resources, and invite developers to visit Booth 500 downstairs for hands-on Q&A and swag.
Elliott argues that agents represent the primary vehicle through which both individuals and enterprises will ultimately realize the true value and promise of large language models. While the industry is saturated with hype surrounding agents, extracting tangible enterprise value has historically proven difficult. In previous years, developer attempts to operationalize agents hit several critical roadblocks:
```mermaid flowchart TD accTitle: Core Challenges in Agent Development subgraph Fragmentation["Ecosystem Fragmentation"] A["Rapidly changing models<br/>(Daily / weekly releases)"] B["Fragmented open-source tools & vendors"] C["High integration friction"] end subgraph EnterpriseGaps["Production Bottlenecks"] D["Lack of MLOps & lifecycle management"] E["Missing enterprise governance & trust"] end Fragmentation --> EnterpriseGaps ```
To transition agents from brittle proof-of-concepts into reliable enterprise software, the ecosystem requires three foundational pillars: - **Developer Toolkits:** Frameworks and libraries that accelerate development speed and eliminate boilerplate. - **Open Protocols:** Standardized communication mechanisms allowing disparate models, tools, and agents to converse seamlessly. - **Enterprise Agentic Platforms:** Scalable infrastructure providing operational tooling, monitoring, governance, and model trust.
---
[02:52](https://www.youtube.com/watch?v=72zGRb3CpFw&t=172s) The Evolution of AI: From Raw Prompts to Multi-Agent Swarms
Tracing the rapid architectural evolution of generative AI over recent years, Elliott breaks down the journey across five distinct paradigms. AI development began with simple prompt-and-response interactions, which suffered heavily from hallucinations, stale knowledge cutoffs, and poor accuracy. The first major leap arrived roughly eighteen months prior with Retrieval-Augmented Generation (RAG), grounding model completions in external vector databases and enterprise documents. The industry then advanced to function calling, enabling models to break out of closed loops to query live search engines, invoke tools, and hit external web APIs.
```mermaid flowchart LR accTitle: Five Phases of Generative AI Evolution P1["1. Raw Prompts<br/>(Hallucinations & static data)"] --> P2["2. RAG<br/>(Grounded in vector DBs)"] P2 --> P3["3. Function Calling<br/>(External APIs & Google Search)"] P3 --> P4["4. Reasoning Loops & Many Tools<br/>(Model-driven orchestration)"] P4 --> P5["5. Multi-Agent Systems<br/>(Collaborative swarms via A2A)"] ```
Looking at 2025 and 2026, state-of-the-art agent architectures are defined by reasoning loops coordinating across wide tool suites, transitioning into true multi-agent collaboration. In this target state, specialized agents do not merely communicate sequentially—they actively collaborate to tackle complex objectives. Elliott highlights his long-term vision of having "thousands or even millions of agents sort of swarming to try to solve problems," an ambition that depends entirely on open industry protocols.
At its core, any agentic system distills into three foundational architectural building blocks:
```mermaid flowchart TD accTitle: Core Triad of Agentic Architecture subgraph AgentCore["Agent Architecture Triad"] O["Orchestration<br/>(Workflows & control flow)"] M["Models<br/>(Decision-making & reasoning)"] T["Tools & APIs<br/>(Grounding, actions & data)"] end M <--> O O <--> T ```
---
[05:20](https://www.youtube.com/watch?v=72zGRb3CpFw&t=320s) Google Cloud's Four Pillars for Agentic AI
Unveiling Google's agentic stack, Elliott details four core components designed to address the developer toolkit, data interoperability, managed operations, and multi-agent protocols. Crucially, three of the four components in the stack are open source or open protocols, reflecting Google's commitment to avoiding vendor lock-in.
```mermaid flowchart TD accTitle: Google Cloud Agentic AI Stack subgraph OpenLayer["Open Source & Open Protocols"] ADK["Agent Development Kit (ADK)<br/>• Code-first client framework<br/>• Open source (announced April)"] MCP["Model Context Protocol (MCP)<br/>• Standardized data & context protocol"] A2A["Agent2Agent (A2A)<br/>• Multi-agent collaboration protocol"] end subgraph ManagedLayer["Managed Enterprise Infrastructure"] AE["Vertex AI Agent Engine<br/>• Managed runtime & scaling<br/>• Security, ops & governance (Paid)"] end ADK <--> MCP ADK <--> AE ADK <--> A2A ```
- **Agent Development Kit (ADK):** The open-source centerpiece of Google's agent tooling, announced in April. Engineered specifically "by software developers for software developers" rather than being shaped purely by machine learning research or academic theory. - **Model Context Protocol (MCP):** The emerging industry standard protocol for feeding real-time context and structured external data directly into agents. - **Vertex AI Agent Engine:** The fully managed runtime and enterprise orchestration layer. As Google Cloud's paid enterprise tier, it supplies the MLOps, infrastructure scaling, automated management, and security governance required for mission-critical enterprise production. - **Agent2Agent (A2A) Protocol:** An open standard facilitating high-fidelity communication, coordination, and collaborative multi-agent problem-solving.
---
[07:14](https://www.youtube.com/watch?v=72zGRb3CpFw&t=434s) The Agent Development Kit (ADK): Core Tenets and Capabilities
Positioned as the "crown jewels" and the star of the stack, the Agent Development Kit (ADK) is an open-source, client-side framework focused on code-first development without restrictive "black box" abstractions. Elliott emphasizes three architectural principles that govern ADK:
1. **Model Agnostic:** While optimized to leverage Google's Gemini models ("Gemini rocks. Gemini always does really well"), ADK explicitly supports third-party and open-weight models across the board. 2. **Deployment Agnostic:** Agents built with ADK can run on Vertex AI Agent Engine, serverless container environments like Cloud Run, container clusters on Google Kubernetes Engine (GKE), or completely on-premises on self-hosted customer infrastructure. 3. **Built for Interoperability:** Designed from the start around open protocols so individual agents can easily integrate into broader multi-agent ecosystems.
Beyond these high-level principles, Elliott highlights the core technical capabilities that make ADK distinct: - **Flexible Workflow Orchestration:** Developers can configure dynamic, reasoning-driven orchestration where the LLM decides runtime tool execution paths, or construct strictly deterministic, hardcoded workflows required for enterprise compliance and repeatability. - **Developer-Centric IDE Experience:** Direct, transparent code interfaces with no opaque abstractions, letting engineers work with standard code tooling. - **Native Multimodal Bidirectional Streaming:** Full support for real-time, low-latency streaming of video, image, and text inputs and outputs across Gemini, Vertex AI, and ADK. - **Built-in Evaluations (Evals):** Integrated testing and benchmarking suites to monitor, evaluate, and assure model accuracy and agent execution quality before deployment. - **Deployment-Ready Architecture:** Clean transitions from local developer prototyping directly into production environments.
[09:47](https://www.youtube.com/watch?v=72zGRb3CpFw&t=587s) Deployment Pathways and Integrating the Model Context Protocol (MCP)
A major sentiment across Reddit and online developer communities regarding Google's Agent Development Kit (ADK) is appreciation that production deployment was never treated as an afterthought. Developing an agent is only the first hurdle; developers must subsequently package and host it on an accessible endpoint. With ADK, the agent can be packaged cleanly into a container and deployed directly to Vertex AI Agent Engine or Cloud Run, or developers can self-manage the deployment on standard Docker hosts, Google Kubernetes Engine (GKE), or local on-premises infrastructure. This flexible deployment model represents one of ADK’s most defining strengths.
Moving across the stack, the Model Context Protocol (MCP)—an open protocol originally spearheaded by Anthropic—has rapidly become an industry standard for connecting AI applications to tools and external data sources. The community rush to build and operate MCP servers has made standardized tool interaction widespread. ADK and MCP are fundamentally complementary rather than competing technologies: developers can either consume existing MCP servers directly within ADK agents or expose native ADK tools outward through an MCP server. Combining ADK orchestration with MCP connectivity gives developers a direct, flexible route toward production-ready tooling.
- **Deployment Targets:** Containerized deployment across Vertex AI Agent Engine, fully managed Cloud Run, self-managed Docker, GKE clusters, or on-prem servers. - **MCP Integration Modes:** Bi-directional interoperability allows agents to invoke external MCP servers as tools or serve internal ADK capabilities over MCP.
[11:34](https://www.youtube.com/watch?v=72zGRb3CpFw&t=694s) Vertex AI Agent Engine: Enterprise Infrastructure and Memory Management
Within Google's agentic stack, Vertex AI Agent Engine stands out as the core commercial managed runtime. Designed to liberate engineering teams from the toil of managing raw infrastructure, Agent Engine allows developers to focus purely on business and application logic. It handles the operational plumbing that engineering teams typically dread maintaining or rely on dedicated specialists to configure, delivering turnkey scalability and resilience.
A central highlight of Agent Engine is state management. As conversational and multi-turn workflows grow more complex, handling short-term working memory alongside persistent long-term memory across sessions has become a pivotal challenge in modern AI architectures. Beyond memory orchestration, the platform natively provides end-to-end tracing, centralized logging, runtime monitoring, identity and access management, and secure sandbox code execution environments.
- **State Management:** Turnkey handling of short-term conversational context and long-term persistent memory storage. - **Operational Infrastructure:** Fully managed execution handling identity management, observability (monitoring, logging, tracing), and sandboxed dynamic code execution.
[12:19](https://www.youtube.com/watch?v=72zGRb3CpFw&t=739s) The Agent2Agent (A2A) Protocol: Enabling Autonomous Collaboration
The final pillar of the architecture is the Agent2Agent (A2A) protocol, a lightweight specification enabling disparate, modular agents to interact autonomously. Designed so that "black boxes can talk to each other," A2A establishes a vendor-neutral standard for agents to discover each other's capabilities and orchestrate complex, multi-party tasks. Although originally developed by Google, the protocol was contributed directly to the Linux Foundation, where a broad board of major cloud and AI vendors actively oversees its open governance and ecosystem adoption.
A2A structures agent collaboration through standardized primitives. Agents publish an "Agent Card" that advertises what the agent does, its operational bounds, and its exposed capabilities. When an orchestrator—such as a top-level strategy agent—determines it needs specialized support, it invokes peer agents by dispatching discrete tasks, receiving updates through real-time streaming and asynchronous push notifications. This pattern decouples specialized risk, audit, and operational agents into modular microservices that can be composed on demand.
```mermaid flowchart LR accTitle: Agent2Agent Protocol Interaction Flow subgraph ClientAgent["Orchestrating Agent"] SA["Strategy Agent"] end
subgraph A2ALayer["A2A Protocol Interface"] direction TB AC["Agent Card<br/>(Capability Advertisement)"] TD["Task Dispatch & Execution"] PS["Push Notifications & Streaming"] end
subgraph ExternalAgents["Collaborating Agents"] direction TB RA["Risk Assessment Agent"] BB["Black-Box Specialist Agent"] end
SA --> AC AC --> TD TD --> RA TD --> BB RA --> PS BB --> PS PS --> SA ```
- **Open Governance:** Seeded by Google and governed by the Linux Foundation with cross-industry vendor backing. - **Core Primitives:** Agent Cards for capability discovery, structured task assignments, and dual push-notification/streaming channels for asynchronous feedback.
[14:06](https://www.youtube.com/watch?v=72zGRb3CpFw&t=846s) Developer Call to Action: Tooling, Documentation, and Next Steps
Reflecting on the evolution of agentic architectures over the past year, modern multi-agent systems have advanced rapidly beyond simple prompts into sophisticated reasoning loops, complex tool calling, and federated agent ecosystems. Google's agentic stack encapsulates this complete hierarchy: ADK serving as the foundational development layer, MCP providing universal data connectivity, Vertex AI Agent Engine delivering managed enterprise runtimes, and A2A unlocking collaborative multi-agent communication.
To get started hands-on, developers can install the core toolkits via Python packaging: running `pip install google-adk` provides immediate access to ADK, supported by an open GitHub repository, 50 to 60 pages of launch documentation drafted by the advocacy team, and eight to ten fully runnable sample agent implementations. Developers looking to explore multi-agent communication can similarly install `pip install a2a-sdk`. After concluding the presentation, attendees were invited to connect on LinkedIn for ongoing updates on Google's agent ecosystem, visit the conference exhibition booth to view live demonstrations and pick up cable organizer bags, and join the evening cocktail hour.
- **ADK Package & Docs:** Available via `pip install google-adk`, backed by comprehensive documentation and 8–10 official sample agents. - **A2A SDK:** Installed via `pip install a2a-sdk` for immediate prototyping of multi-agent federation.
## Notable quotes > [00:04](https://www.youtube.com/watch?v=72zGRb3CpFw&t=4s) I'm the last one standing between you and the cocktail hour. Uh, so I plan to take three hours. No. Okay. — Dave Elliott
> [02:52](https://www.youtube.com/watch?v=72zGRb3CpFw&t=172s) thousands or even millions of agents sort of swarming to try to solve problems — Dave Elliott
> [05:20](https://www.youtube.com/watch?v=72zGRb3CpFw&t=320s) by software developers for software developers — Dave Elliott
> [07:14](https://www.youtube.com/watch?v=72zGRb3CpFw&t=434s) Gemini rocks. Gemini always does really well — Dave Elliott
> [12:19](https://www.youtube.com/watch?v=72zGRb3CpFw&t=739s) black boxes can talk to each other — Dave Elliott
> [14:06](https://www.youtube.com/watch?v=72zGRb3CpFw&t=846s) pip install google-adk — Dave Elliott
> [14:06](https://www.youtube.com/watch?v=72zGRb3CpFw&t=846s) pip install a2a-sdk — Dave Elliott
## Mentioned Dave Elliott, Google, Google Cloud, Ai4, Gemini, Agent Development Kit (ADK), Model Context Protocol (MCP), Agent2Agent (A2A), Vertex AI Agent Engine, Cloud Run, Google Kubernetes Engine (GKE), Docker, Anthropic, Linux Foundation, Python, GitHub, LinkedIn, Reddit
## Video description Dave Elliott, Head of Developer Advocacy for AI, Google Cloud Abstracts
How can you effectively build and deploy powerful AI agents that move beyond simple prompts? This session dives into the core components of an agentic stack, exploring how orchestration, models, and tools combine to create intelligent, autonomous systems. We'll unveil Google Cloud's agentic stack, highlighting the Agent Development Kit (ADK), Model Context Protocol (MCP), and Agent2Agent (A2A) protocol, and demonstrate how they enable robust agent development and interoperability. Join us to learn how to leverage these innovations to unlock the full potential of AI agents in your applications. How can you effectively build and deploy powerful AI agents that move beyond simple prompts? This session dives into the core components of an agentic stack, exploring how orchestration, models, and tools combine to create intelligent, autonomous systems. We'll unveil Google Cloud's agentic stack, highlighting the Agent Development Kit (ADK), Model Context Protocol (MCP), and Agent2Agent (A2A) protocol, and demonstrate how they enable robust agent development and interoperability. Join us to learn how to leverage these innovations to unlock the full potential of AI agents in your applications.
[Source](https://www.youtube.com/watch?v=72zGRb3CpFw)