docs(index): restructure homepage information and add missing sections

.github/actions/spelling/allow.txt

@@ -28,6 +28,7 @@
 Blogs
 CAs
 CLIs
+CTAs
 Camry
 Cjava
 Cpzuhi
@@ -307,7 +308,7 @@
 openaitx
 openapis
 openapiv
 openapiv2
 oreilly
 postgres
 postgresql
@@ -347,6 +348,7 @@
 svn
 systemctl
 tablefmt
+tagline
 tagwords
 tasksget
 taskslist
@@ -365,7 +367,7 @@
 ugc
 undoc
 utm
 venv-docs
 versioned
 vnd
 voa

README.md

@@ -40,7 +40,7 @@
 <!-- markdownlint-disable MD041 -->
 <div style="text-align: center;">
   <div class="centered-logo-text-group">
-    <img src="docs/assets/a2a-logo-black.svg" alt="Agent2Agent Protocol Logo" width="100">
+    <img src="docs/assets/a2a_logo/color/SVG/a2a_color.svg" alt="Agent2Agent Protocol Logo" width="100">
     <h1>Agent2Agent (A2A) Protocol</h1>
   </div>
 </div>

docs/index.md

@@ -1,41 +1,58 @@
 ---
 hide:
   - toc
+  - navigation
 ---
 
 <!-- markdownlint-disable MD041 -->
-<div style="text-align: center;">
+<div style="text-align: center;" markdown>
   <div class="centered-logo-text-group">
-    <img src="assets/a2a-logo-black.svg" alt="Agent2Agent Protocol Logo" width="100">
-    <h1>Agent2Agent (A2A) Protocol</h1>
+    <h1><img src="assets/a2a_logo/color/SVG/a2a_color.svg" alt="Agent2Agent Protocol Logo" width="500"></h1>
   </div>
+
+  <p class="hero-tagline">An open protocol enabling communication and interoperability between opaque agentic applications.</p>
+
+  [Get started](./tutorials/python/1-introduction.md){ .md-button .md-button--primary }
+  [Read the spec](./specification.md){ .md-button }
 </div>
 
 ## What is A2A Protocol?
 
-Welcome to the **official documentation** for the **Agent2Agent (A2A) Protocol**, an open standard designed to enable seamless communication and collaboration between AI agents.
-
-Originally developed by Google and now donated to the Linux Foundation, A2A provides the definitive common language for agent interoperability in a world where agents are built using diverse frameworks and by different vendors.
+The **Agent2Agent (A2A) Protocol** is an open standard for seamless communication and collaboration between AI agents. In a world where agents are built using diverse frameworks and by different vendors, A2A provides the definitive common language for agent interoperability.
 
 !!! abstract ""
     Build with
     **[![ADK Logo](https://google.github.io/adk-docs/assets/agent-development-kit.png){class="twemoji lg middle"} ADK](https://google.github.io/adk-docs/)** _(or any framework)_,
     equip with **[![MCP Logo](https://modelcontextprotocol.io/mcp.png){class="twemoji lg middle"} MCP](https://modelcontextprotocol.io)** _(or any tool)_,
     and communicate with
-    **![A2A Logo](./assets/a2a-logo-black.svg){class="twemoji lg middle"} A2A**,
+    **![A2A Logo](./assets/a2a_logo/icon/color/SVG/a2a_icon_color.svg){class="twemoji lg middle"} A2A**,
     to remote agents, local agents, and humans.
 
-## Get started with A2A
+## Key Features
 
 <div class="grid cards" markdown>
 
-- :material-play-circle:{ .lg .middle } **Video** Intro in <8 min
+- :material-account-group-outline:{ .lg .middle } **Interoperability**
 
-    <iframe class="video-container" src="https://www.youtube.com/embed/Fbr_Solax1w?si=QxPMEEiO5kLr5_0F" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
+    Connect agents built on different platforms (LangGraph, CrewAI, Semantic Kernel, custom solutions) to create powerful, composite AI systems.
 
-- :material-play-circle:{ .lg .middle } **Course** [DeepLearning.AI](https://deeplearning.ai) - Intro to A2A
+- :material-lan-connect:{ .lg .middle } **Complex Workflows**
 
-    [![A2A DeepLearning.AI](https://img.youtube.com/vi/4gYm0Rp7VHc/maxresdefault.jpg)](https://goo.gle/dlai-a2a)
+    Enable agents to delegate sub-tasks, exchange information, and coordinate actions to solve complex problems that a single agent cannot.
+
+- :material-shield-key-outline:{ .lg .middle } **Secure & Opaque**
+
+    Agents interact without needing to share internal memory, tools, or proprietary logic, ensuring security and preserving intellectual property.
+
+- :material-puzzle-outline:{ .lg .middle } **Extensible**
+
+    Add capabilities through formal protocol [extensions and custom bindings](./topics/extension-and-binding-governance.md), governed by a tiered promotion process so the core stays stable.
+
+</div>
+
+## Get started with A2A
+
+<div class="grid cards" markdown>
 
 - :material-book-open:{ .lg .middle } **Read the Introduction**
 
@@ -55,9 +72,7 @@ Originally developed by Google and now donated to the Linux Foundation, A2A prov
 
     Build your first A2A-compliant agent with our step-by-step Python quickstart.
 
-    [:octicons-arrow-right-24: Python Tutorial](./tutorials/python/1-introduction.md)
-
-    [:octicons-arrow-right-24: Walkthrough with AI Agent Frameworks](https://github.com/holtskinner/A2AWalkthrough)
+    [:octicons-arrow-right-24: Hands-on-Tutorial](./tutorials/python/1-introduction.md)
 
 - :material-code-braces:{ .lg .middle } **Explore Code Samples**
 
@@ -73,58 +88,67 @@ Originally developed by Google and now donated to the Linux Foundation, A2A prov
 
     [:fontawesome-brands-java: Java](https://github.com/a2aproject/a2a-java)
 
-    [:octicons-code-24: C#/.NET](https://github.com/a2aproject/a2a-dotnet)
+    [:material-language-csharp: C#/.NET](https://github.com/a2aproject/a2a-dotnet)
 
     [:fontawesome-brands-golang: Golang](https://github.com/a2aproject/a2a-go)
 
+    [:fontawesome-brands-rust: Rust](https://github.com/a2aproject/a2a-rust)
+
+- :material-play-circle:{ .lg .middle } **Video** Intro in under 8 min
+
+    <iframe class="video-container" src="https://www.youtube.com/embed/Fbr_Solax1w?si=QxPMEEiO5kLr5_0F" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
+
+- :material-play-circle:{ .lg .middle } **Course** [DeepLearning.AI](https://deeplearning.ai) - Intro to A2A
+
+    [![A2A DeepLearning.AI](https://img.youtube.com/vi/4gYm0Rp7VHc/maxresdefault.jpg)](https://goo.gle/dlai-a2a)
+
 </div>
 
-## Why use the A2A Protocol
+## How A2A Works with MCP
+
+The Model Context Protocol (MCP) and the A2A Protocol are not competitors — they are highly complementary. They solve two different problems and are designed to work together.
+
+- **MCP is for agent-to-tool communication:** it standardizes how an agent connects to its tools, APIs, and resources to get information. See [Model Context Protocol](https://modelcontextprotocol.io/).
+- **A2A is for agent-to-agent communication:** as a universal, decentralized standard, A2A lets independent agents — including those using MCP — discover each other, delegate tasks, and share results.
+
+Use MCP to equip an individual agent with the specific tools it needs to do its job (e.g., access to a GitHub repository or a SQL database). Use A2A to let that specialized agent securely collaborate with other agents across different frameworks.
 
 <div style="text-align:center">
 
 ```mermaid
-graph LR
+flowchart LR
     User(🧑‍💻 User) <--> ClientAgent(🤖 Client Agent)
-    ClientAgent --> A2A1(**↔️ A2A**) --> RemoteAgent1(🤖 Remote Agent 1)
-    ClientAgent --> A2A2(**↔️ A2A**) --> RemoteAgent2(🤖 Remote Agent 2)
+    RemoteAgent(🤖 Remote Agent)
+    RemoteTool(⚙️ Remote Tool)
+    ClientAgent -- Using <img src="assets/a2a_logo/icon/color/SVG/a2a_icon_color.svg" alt="Agent2Agent Protocol Logo" height="40" width="40"> --> RemoteAgent
+    ClientAgent -- Using <img src="https://modelcontextprotocol.io/mcp.png" alt="Agent2Agent Protocol Logo" height="40" width="40"> --> RemoteTool
+
 
     style User fill:#fdebd0,stroke:#e67e22,stroke-width:2px
     style ClientAgent fill:#d6eaf8,stroke:#3498db,stroke-width:2px
-    style RemoteAgent1 fill:#d6eaf8,stroke:#3498db,stroke-width:2px
-    style RemoteAgent2 fill:#d6eaf8,stroke:#3498db,stroke-width:2px
-    style A2A1 fill:#ebedef,stroke:#909497,stroke-width:2px
-    style A2A2 fill:#ebedef,stroke:#909497,stroke-width:2px
+    style RemoteAgent fill:#d6eaf8,stroke:#3498db,stroke-width:2px
+    style RemoteTool fill:#d6eaf8,stroke:#3498db,stroke-width:2px
 ```
 
 </div>
 
-<div class="grid cards" markdown>
-
-- :material-account-group-outline:{ .lg .middle } **Interoperability**
-
-    Connect agents built on different platforms (LangGraph, CrewAI, Semantic Kernel, custom solutions) to create powerful, composite AI systems.
-
-- :material-lan-connect:{ .lg .middle } **Complex Workflows**
-
-    Enable agents to delegate sub-tasks, exchange information, and coordinate actions to solve complex problems that a single agent cannot.
+[:octicons-arrow-right-24: A2A and MCP — deeper dive](./topics/a2a-and-mcp.md)
 
-- :material-shield-key-outline:{ .lg .middle } **Secure & Opaque**
+## What A2A Is Not
 
-    Agents interact without needing to share internal memory, tools, or proprietary logic, ensuring security and preserving intellectual property.
+A2A is a focused protocol. To set expectations, here is what it explicitly does not try to be:
 
-</div>
+- **Not an agent development kit** like LangGraph, CrewAI, or ADK for building agentic applications. A2A is the communication layer between agents built with any of these.
+- **Not a sub-agent or tool-call protocol.** A2A does not specify how an agent talks to its own sub-agents or how it invokes tools — use your framework's native primitives, or MCP, for those.
+- **Not a replacement for [MCP](https://modelcontextprotocol.io/).** MCP standardizes agent-to-tool communication; A2A standardizes agent-to-agent communication. They are complementary (see [above](#how-a2a-works-with-mcp)).
+- **Not an interactive messaging app** like Slack, Discord, WhatsApp, or Telegram. A2A is a machine-to-machine protocol for autonomous agents.
 
----
+## Governance & Open Source
 
-## How does A2A work with MCP?
+A2A was originally developed by Google and donated to the Linux Foundation. It is maintained by a Technical Steering Committee with representatives from AWS, Cisco, Google, IBM Research, Microsoft, Salesforce, SAP, and ServiceNow, and supported by a broad community of [partners](./partners.md).
 
-![A2A MCP Graphic](assets/a2a-mcp-readme.png){width="60%"}
-{style="text-align: center; margin-bottom:1em; margin-top:1em;"}
+For details on how the project is run, see [`GOVERNANCE.md`](https://github.com/a2aproject/A2A/blob/main/GOVERNANCE.md) and [`MAINTAINERS.md`](https://github.com/a2aproject/A2A/blob/main/MAINTAINERS.md).
 
-A2A and [Model Context Protocol (MCP)](https://modelcontextprotocol.io/) are complementary standards for building robust agentic applications:
+## License
 
-- **Model Context Protocol (MCP)**: Provides [agent-to-tool communication](https://cloud.google.com/discover/what-is-model-context-protocol). It's a complementary standard that standardizes how an agent connects to its tools, APIs, and resources to get information.
-- **IBM ACP**: [Incorporated into the A2A Protocol](https://github.com/orgs/i-am-bee/discussions/5)
-- **Cisco agntcy**: A framework that provides components to the Internet of Agents with discovery, group communication, identity and observability and leverages A2A and MCP for agent communication and tool calling.
-- **A2A**: Provides agent-to-agent communication. As a universal, decentralized standard, A2A acts as the public internet that allows [ai agents](https://cloud.google.com/discover/what-are-ai-agents)—including those using MCP, or built with frameworks like agntcy—to interoperate, collaborate, and share their findings.
+The A2A Protocol is licensed under the [Apache License 2.0](https://github.com/a2aproject/A2A/blob/main/LICENSE) and welcomes [contributions](https://github.com/a2aproject/A2A/blob/main/CONTRIBUTING.md) from the community.

docs/stylesheets/custom.css

@@ -41,6 +41,15 @@
   text-align: left;
 }
 
+/* Hero tagline: sits between the logo and the primary CTAs. */
+.hero-tagline {
+  font-size: 1.25rem;
+  line-height: 1.5;
+  color: var(--md-default-fg-color--light);
+  max-width: 42em;
+  margin: 1em auto 1.75em;
+}
+
 .install-command-container {
   max-width: 600px;
   margin: 2.5em auto;

mkdocs.yml

@@ -79,8 +79,8 @@ theme:
   font:
     text: Google Sans
     code: Roboto Mono
-  logo: assets/a2a-logo-white.svg
-  favicon: assets/a2a-logo-black.svg
+  logo: assets/a2a_logo/icon/white/SVG/a2a_icon_white.svg
+  favicon: assets/a2a_logo/icon/white/SVG/a2a_icon_white.svg
   icon:
     repo: fontawesome/brands/github
     view: material/pencil-box-multiple