google--adk-python/contributing/samples/managed_agent/custom_agent

Managed Agent: Create and Use a Custom Agent

For setup, authentication, backends, and background on ManagedAgent, see the ManagedAgent guide.

Overview

This sample demonstrates the control-plane lifecycle of a custom managed agent: creating a persistent, named agent resource — its persona and server-side tools baked in — then driving it and deleting it.

You do not need a custom resource just to set a persona or server-side tools. ManagedAgent accepts both inline: instruction=... for a persona (see the system_instruction sample) and tools=[google_search] for server-side tools (see the basic sample). Create a custom resource when you instead want a reusable, server-managed agent that other apps and sessions can share by id.

This module drives that lifecycle: run it with --create to provision the resource (reusing the genai client ManagedAgent already holds, root_agent.api_client, which exposes both interactions and agent create/delete), then drive root_agent with adk web / adk run, and --delete to remove it.

Setup

Custom-agent creation requires the GEAP / Vertex backend (global location); the Gemini API backend cannot create agent resources. For backend selection, authentication, and credentials, see the ManagedAgent guide.

Usage

# 1. Create the custom agent (once).
python contributing/samples/managed_agent/custom_agent/agent.py --create

# 2. Chat with it. Provisioning can take a few minutes (longer for the first
#    agent in a project), so wait a moment after --create before the first turn.
adk run contributing/samples/managed_agent/custom_agent
#    or: adk web

# 3. Delete it when done.
python contributing/samples/managed_agent/custom_agent/agent.py --delete

Creation is asynchronous: --create returns before the agent is fully ready, so if the first turn fails with a "not found" / "being created" error, wait a few seconds and retry.

Sample Inputs

Answers are grounded in live search, so exact text varies:

• What are the most significant AI announcements this week?

  The created agent's persona makes it answer concisely and cite its sources, using server-side google_search.

• Summarize that in one sentence.

  A follow-up turn that reuses the recovered interaction (multi-turn chaining).

Graph

graph LR
    User -->|message| CustomManagedAgent
    CustomManagedAgent -->|interactions.create| ManagedAgentsAPI
    ManagedAgentsAPI -->|server-side google_search| ManagedAgentsAPI
    ManagedAgentsAPI -->|streamed events| CustomManagedAgent
    CustomManagedAgent -->|answer| User

How To

• Define the custom agent: pass a system_instruction (persona) and server-side tools (here {'type': 'google_search'}) to client.agents.create(...), extending the antigravity-preview-05-2026 base agent.
• Reuse the ManagedAgent client: root_agent.api_client is the genai client ManagedAgent already holds; its agents.create / agents.delete cover the control plane.
• Provision a sandbox: ManagedAgent(environment={'type': 'remote'}) gives each interaction a remote sandbox — optional, and omitted by samples whose tools do not need one (see remote_mcp).
• Run it: --create provisions, --delete removes; in between, root_agent is a normal BaseAgent, so adk web / adk run (or a Runner) drive it.