guides: add agentic guide (#22937)

<!--Delete sections as needed -->

## Description

Add agentic guide
https://deploy-preview-22937--docsdocker.netlify.app/guides/agentic-ai/

## Related issues or tickets

ENGDOCS-2770

Depends on:
- https://github.com/docker/docs/pull/22935
- https://github.com/docker/docs/pull/22910

## Reviews

<!-- Notes for reviewers here -->
<!-- List applicable reviews (optionally @tag reviewers) -->

- [ ] Technical review
- [ ] Editorial review

---------

Signed-off-by: Craig <craig.osterhout@docker.com>
Co-authored-by: Usha Mandya <47779042+usha-mandya@users.noreply.github.com>
Co-authored-by: aevesdocker <allie.sadler@docker.com>

content/guides/agentic-ai.md

@@ -0,0 +1,394 @@
+---
+title: Build and run agentic AI applications with Docker
+linktitle: Agentic AI applications
+keywords: AI, Docker, Model Runner, MCP Toolkit, Docker Offload, AI agents, application development
+summary: |
+  Learn how to create AI agent applications using Docker Model Runner, MCP Toolkit, and Docker Offload.
+params:
+  tags: [AI]
+  time: 30 minutes
+---
+
+## Introduction
+
+Agentic applications are transforming how software gets built. These apps don't
+just respond, they decide, plan, and act. They're powered by models,
+orchestrated by agents, and integrated with APIs, tools, and services in real
+time.
+
+All these new agentic applications, no matter what they do, share a common
+architecture. It's a new kind of stack, built from three core components:
+
+- Models: These are your GPTs, CodeLlamas, Mistrals. They're doing the
+  reasoning, writing, and planning. They're the engine behind the intelligence.
+
+- Agent: This is where the logic lives. Agents take a goal, break it down, and
+  figure out how to get it done. They orchestrate everything. They talk to the
+  UI, the tools, the model, and the gateway.
+
+- MCP gateway: This is what links your agents to the outside world, including
+  APIs, tools, and services. It provides a standard way for agents to call
+  capabilities via the Model Context Protocol (MCP).
+
+Docker makes this AI-powered stack simpler, faster, and more secure by unifying
+models, tool gateways, and cloud infrastructure into a developer-friendly
+workflow that uses Docker Compose.
+
+![A diagram of the agentic stack](./images/agentic-ai-diagram.webp)
+
+This guide walks you through the core components of agentic development and
+shows how Docker ties them all together with the following tools:
+
+- [Docker Model Runner](../manuals/ai/model-runner/_index.md) lets you run LLMs
+  locally with simple command and OpenAI-compatible APIs.
+- [Docker MCP Catalog and
+  Toolkit](../manuals/ai/mcp-catalog-and-toolkit/_index.md) helps you discover
+  and securely run external tools, like APIs and databases, using the Model
+  Context Protocol (MCP).
+- [Docker MCP Gateway](/ai/mcp-gateway/) lets you orchestrate and manage MCP servers.
+- [Docker Offload](/offload/) provides a powerful, GPU-accelerated
+  environment to run your AI applications with the same Compose-based
+  workflow you use locally.
+- [Docker Compose](/manuals/ai/compose/models-and-compose.md) is the tool that ties it all
+  together, letting you define and run multi-container applications with a
+  single file.
+
+For this guide, you'll start by running the app in Docker Offload, using the
+same Compose workflow you're already familiar with. Then, if your machine
+hardware supports it, you'll run the same app locally using the same workflow.
+Finally, you'll dig into the Compose file, Dockerfile, and app to see how it all
+works together.
+
+## Prerequisites
+
+To follow this guide, you need to:
+
+ - [Install Docker Desktop 4.43 or later](../get-started/get-docker.md)
+ - [Enable Docker Model Runner](/manuals/ai/model-runner.md#enable-dmr-in-docker-desktop)
+ - [Join Docker Offload Beta](/offload/quickstart/)
+
+## Step 1: Clone the sample application
+
+You'll use an existing sample application that demonstrates how to connect a
+model to an external tool using Docker's AI features.
+
+```console
+$ git clone https://github.com/docker/compose-for-agents.git
+$ cd compose-for-agents/adk/
+```
+
+## Step 2: Run the application with Docker Offload
+
+You'll start by running the application in Docker Offload, which provides a
+managed environment for running AI workloads. This is ideal if you want to
+leverage cloud resources or if your local machine doesn't meet the hardware
+requirements to run the model locally. Docker Offload includes support for
+GPU-accelerated instances, making it ideal for compute-intensive workloads like
+AI model inference.
+
+To run the application with Docker Offload, follow these steps:
+
+1. Sign in to the Docker Desktop Dashboard.
+2. In a terminal, start Docker Offload by running the following command:
+
+   ```console
+   $ docker offload start
+   ```
+
+   When prompted, choose the account you want to use for Docker Offload and select
+   **Yes** when prompted **Do you need GPU support?**.
+
+3. In the `adk/` directory of the cloned repository, run the following command
+   in a terminal to build and run the application:
+
+   ```console
+   $ docker compose up
+   ```
+
+   The first time you run this command, Docker pulls the model from Docker Hub,
+   which may take some time.
+
+   The application is now running with Docker Offload. Note that the Compose workflow
+   is the same when using Docker Offload as it is locally. You define your
+   application in a `compose.yaml` file, and then use `docker compose up` to build
+   and run it.
+
+4. Visit [http://localhost:8080](http://localhost:8080). Enter a correct or
+   incorrect fact in the prompt and hit enter. An agent searches DuckDuckGo to
+   verify it and another agent revises the output.
+
+   ![Screenshot of the application](./images/agentic-ai-app.png)
+
+5. Press ctrl-c in the terminal to stop the application when you're done.
+
+6. Run the following command to stop Docker Offload:
+
+   ```console
+   $ docker offload stop
+   ```
+
+## Step 3: Optional. Run the application locally
+
+If your machine meets the necessary hardware requirements, you can run the
+entire application stack locally using Docker Compose. This lets you test the
+application end-to-end, including the model and MCP gateway, without needing to
+run in the cloud. This particular example uses the [Gemma 3 4B
+model](https://hub.docker.com/r/ai/gemma3) with a context size of `10000`.
+
+Hardware requirements:
+ - VRAM: 3.5 GB
+ - Storage: 2.31 GB
+
+If your machine exceeds those requirements, consider running the application with a larger
+context size or a larger model to improve the agents performance. You can easily
+update model and context size in the `compose.yaml` file.
+
+To run the application locally, follow these steps:
+
+1. In the `adk/` directory of the cloned repository, run the following command in a
+   terminal to build and run the application:
+
+   ```console
+   $ docker compose up
+   ```
+
+   The first time you run this command, Docker pulls the
+   model from Docker Hub, which may take some time.
+
+2. Visit [http://localhost:8080](http://localhost:8080). Enter a correct or
+   incorrect fact in the prompt and hit enter. An agent searches DuckDuckGo to
+   verify it and another agent revises the output.
+
+3. Press ctrl-c in the terminal to stop the application when you're done.
+
+## Step 4: Review the application environment
+
+You can find the `compose.yaml` file in the `adk/` directory. Open it in a text
+editor to see how the services are defined.
+
+```yaml {collapse=true,title=compose.yaml}
+services:
+  adk:
+    build:
+      context: .
+    ports:
+      # expose port for web interface
+      - "8080:8080"
+    environment:
+      # point adk at the MCP gateway
+      - MCPGATEWAY_ENDPOINT=http://mcp-gateway:8811/sse
+    depends_on:
+      - mcp-gateway
+    models:
+      gemma3 :
+        endpoint_var: MODEL_RUNNER_URL
+        model_var: MODEL_RUNNER_MODEL
+
+  mcp-gateway:
+    # mcp-gateway secures your MCP servers
+    image: docker/mcp-gateway:latest
+    use_api_socket: true
+    command:
+      - --transport=sse
+      # add any MCP servers you want to use
+      - --servers=duckduckgo
+
+models:
+  gemma3:
+    # pre-pull the model when starting Docker Model Runner
+    model: ai/gemma3:4B-Q4_0
+    context_size: 10000 # 3.5 GB VRAM
+    # increase context size to handle search results
+    # context_size: 131000 # 7.6 GB VRAM
+```
+
+The app consists of three main components:
+
+ - The `adk` service, which is the web application that runs the agentic AI
+   application. This service talks to the MCP gateway and model.
+ - The `mcp-gateway` service, which is the MCP gateway that connects the app
+   to external tools and services.
+ - The `models` block, which defines the model to use with the application.
+
+When you examine the `compose.yaml` file, you'll notice two notable elements for the model:
+
+ - A service‑level `models` block in the `adk` service
+ - A top-level `models` block
+
+These two blocks together let Docker Compose automatically start and connect
+your ADK web app to the specified LLM.
+
+> [!TIP]
+>
+> Looking for more models to use? Check out the [Docker AI Model
+> Catalog](https://hub.docker.com/catalogs/models/).
+
+When examining the `compose.yaml` file, you'll notice the gateway service is a
+Docker-maintained image,
+[`docker/mcp-gateway:latest`](https://hub.docker.com/r/docker/agents_gateway).
+This image is Docker's open source [MCP
+Gateway](https://github.com/docker/docker-mcp/) that enables your application to
+connect to MCP servers, which expose tools that models can call. In this
+example, it uses the [`duckduckgo` MCP
+server](https://hub.docker.com/mcp/server/duckduckgo/overview) to perform web
+searches.
+
+>  [!TIP]
+>
+> Looking for more MCP servers to use? Check out the [Docker MCP
+> Catalog](https://hub.docker.com/catalogs/mcp/).
+
+With only a few lines of instructions in a Compose file, you're able to run and
+connect all the necessary services of an agentic AI application.
+
+In addition to the Compose file, the Dockerfile and the
+`entrypoint.sh` script it creates, play a role in wiring up the AI stack at build and
+runtime. You can find the `Dockerfile` in the `adk/` directory. Open it in a
+text editor.
+
+```dockerfile {collapse=true,title=Dockerfile}
+# Use Python 3.11 slim image as base
+FROM python:3.13-slim
+ENV PYTHONUNBUFFERED=1
+
+RUN pip install uv
+
+WORKDIR /app
+# Install system dependencies
+COPY pyproject.toml uv.lock ./
+RUN --mount=type=cache,target=/root/.cache/uv \
+    UV_COMPILE_BYTECODE=1 UV_LINK_MODE=copy \
+    uv pip install --system .
+# Copy application code
+COPY agents/ ./agents/
+RUN python -m compileall -q .
+
+COPY <<EOF /entrypoint.sh
+#!/bin/sh
+set -e
+
+if test -f /run/secrets/openai-api-key; then
+    export OPENAI_API_KEY=$(cat /run/secrets/openai-api-key)
+fi
+
+if test -n "\${OPENAI_API_KEY}"; then
+    echo "Using OpenAI with \${OPENAI_MODEL_NAME}"
+else
+    echo "Using Docker Model Runner with \${MODEL_RUNNER_MODEL}"
+    export OPENAI_BASE_URL=\${MODEL_RUNNER_URL}
+    export OPENAI_MODEL_NAME=openai/\${MODEL_RUNNER_MODEL}
+    export OPENAI_API_KEY=cannot_be_empty
+fi
+exec adk web --host 0.0.0.0 --port 8080 --log_level DEBUG
+EOF
+RUN chmod +x /entrypoint.sh
+
+# Create non-root user
+RUN useradd --create-home --shell /bin/bash app \
+    && chown -R app:app /app
+USER app
+
+ENTRYPOINT [ "/entrypoint.sh" ]
+```
+
+The `entrypoint.sh` has five key environment variables:
+
+- `MODEL_RUNNER_URL`: Injected by Compose (via the service-level `models:`
+  block) to point at your Docker Model Runner HTTP endpoint.
+
+- `MODEL_RUNNER_MODEL`: Injected by Compose to select which model to launch in
+  Model Runner.
+
+- `OPENAI_API_KEY`: If you define an `openai-api-key` secret in your Compose
+  file, Compose will mount it at `/run/secrets/openai-api-key`. The entrypoint
+  script reads that file and exports it as `OPENAI_API_KEY`, causing the app to
+  use hosted OpenAI instead of Model Runner.
+
+- `OPENAI_BASE_URL`: When no real key is present, this is set to
+  `MODEL_RUNNER_URL` so the ADK's OpenAI-compatible client sends requests to
+  Docker Model Runner.
+
+- `OPENAI_MODEL_NAME`: When falling back to Model Runner, the model is prefixed
+  with `openai/` so the client picks up the right model alias.
+
+Together, these variables let the same ADK web server code seamlessly target either:
+
+- Hosted OpenAI: if you supply `OPENAI_API_KEY` (and optionally `OPENAI_MODEL_NAME`)
+- Model Runner: by remapping `MODEL_RUNNER_URL` and `MODEL_RUNNER_MODEL` into the OpenAI client’s expected variables
+
+## Step 5: Review the application
+
+The `adk` web application is an agent implementation that connects to the MCP
+gateway and a model through environment variables and API calls. It uses the
+[ADK (Agent Development Kit)](https://github.com/google/adk-python) to define a
+root agent named Auditor, which coordinates two sub-agents, Critic and Reviser,
+to verify and refine model-generated answers.
+
+The three agents are:
+
+- Critic: Verifies factual claims using the toolset, such as DuckDuckGo.
+- Reviser: Edits answers based on the verification verdicts provided by the Critic.
+- Auditor: A higher-level agent that sequences the
+  Critic and Reviser. It acts as the entry point, evaluating LLM-generated
+  answers, verifying them, and refining the final output.
+
+All of the application's behavior is defined in Python under the `agents/`
+directory. Here's a breakdown of the notable files:
+
+- `agents/agent.py`: Defines the Auditor, a SequentialAgent that chains together
+  the Critic and Reviser agents. This agent is the main entry point of the
+  application and is responsible for auditing LLM-generated content using
+  real-world verification tools.
+
+- `agents/sub_agents/critic/agent.py`: Defines the Critic agent. It loads the
+  language model (via Docker Model Runner), sets the agent’s name and behavior,
+  and connects to MCP tools (like DuckDuckGo).
+
+- `agents/sub_agents/critic/prompt.py`: Contains the Critic prompt, which
+  instructs the agent to extract and verify claims using external tools.
+
+- `agents/sub_agents/critic/tools.py`: Defines the MCP toolset configuration,
+  including parsing `mcp/` strings, creating tool connections, and handling MCP
+  gateway communication.
+
+- `agents/sub_agents/reviser/agent.py`: Defines the Reviser agent, which takes
+  the Critic’s findings and minimally rewrites the original answer. It also
+  includes callbacks to clean up the LLM output and ensure it's in the right
+  format.
+
+- `agents/sub_agents/reviser/prompt.py`: Contains the Reviser prompt, which
+  instructs the agent to revise the answer text based on the verified claim
+  verdicts.
+
+The MCP gateway is configured via the `MCPGATEWAY_ENDPOINT` environment
+variable. In this case, `http://mcp-gateway:8811/sse`. This allows the app to
+use Server-Sent Events (SSE) to communicate with the MCP gateway container,
+which itself brokers access to external tool services like DuckDuckGo.
+
+## Summary
+
+Agent-based AI applications are emerging as a powerful new software
+architecture. In this guide, you explored a modular, chain-of-thought system
+where an Auditor agent coordinates the work of a Critic and a Reviser to
+fact-check and refine model-generated answers. This architecture shows how to
+combine local model inference with external tool integrations in a structured,
+modular way.
+
+You also saw how Docker simplifies this process by providing a suite of tools
+that support local and cloud-based agentic AI development:
+
+- [Docker Model Runner](../manuals/ai/model-runner/_index.md): Run and serve
+  open-source models locally via OpenAI-compatible APIs.
+- [Docker MCP Catalog and
+  Toolkit](../manuals/ai/mcp-catalog-and-toolkit/_index.md): Launch and manage
+  tool integrations that follow the Model Context Protocol (MCP) standard.
+- [Docker MCP Gateway](/ai/mcp-gateway/): Orchestrate and manage
+  MCP servers to connect agents to external tools and services.
+- [Docker Compose](/manuals/ai/compose/models-and-compose.md): Define and run
+  multi-container agentic AI applications with a single file, using the same
+  workflow locally and in the cloud.
+- [Docker Offload](/offload/): Run GPU-intensive AI workloads in a secure, managed
+  cloud environment using the same Docker Compose workflow you use locally.
+
+With these tools, you can develop and test agentic AI applications efficiently,
+locally or in the cloud, using the same consistent workflow throughout.