Agent Registry lets you register AI agents so that developers and orchestrator
agents can discover and invoke their capabilities across your AI ecosystem. By
publishing your agent's
[A2A skills](https://docs.cloud.google.com/agent-registry/skills-architecture.md.txt#standalone-vs-a2a), you help
other developers and orchestrator agents in your organization find and reuse
your work.

Agent Registry integrates with versions `0.3` and `1.0` of the open source
[Agent2Agent (A2A)](https://a2a-protocol.org/latest/) protocol, which lets
agents declare their capabilities and identity in an
[Agent Card](https://docs.cloud.google.com/agent-registry/json-schemas.md.txt#agent-card). Depending on where your
agents run, you can register them using
[automatic registration](https://docs.cloud.google.com/agent-registry/register-agents.md.txt#automatic-registration) or
[manual registration](https://docs.cloud.google.com/agent-registry/register-agents.md.txt#manual-registration).

## Automatic registration

Supported Google Cloud runtimes register your agents
automatically, and built-in Google agents are discoverable without
configuration. Within the
[governance project](https://docs.cloud.google.com/agent-registry/overview.md.txt#governance-project) where
Agent Registry is enabled, automatic registration happens either by default or
through an opt-in deployment step. By default, the registration process operates
at the project level. To automatically aggregate agents across multiple
Google Cloud projects, configure a
[management boundary](https://docs.cloud.google.com/agent-registry/boundaries-and-topology.md.txt).

For information about Google Cloud runtimes that support automatic
registration and the metadata indexed for automatically registered agents, see
[Use automatic registration for agents](https://docs.cloud.google.com/agent-registry/automatic-registration.md.txt).

## Manual registration

Agent Registry uses a central Google Cloud
[governance project](https://docs.cloud.google.com/agent-registry/overview.md.txt#governance-project). The term
*remote* refers to agents hosted outside the governance project in separate
Google Cloud projects, on-premises environments, or external platforms, or
running on Google Cloud runtimes that don't support automatic discovery.
You must use manual registration to add remote agents to the governance
project's registry.

To manually register an agent, use the Google Cloud console, the Google Cloud CLI,
Terraform, or the Agent Registry API to create a `Service` resource that stores the
agent's metadata, including its endpoint URL and configuration. After you create
the `Service` resource, Agent Registry automatically creates a read-only
`Agent` resource that you can use for
[discovery](https://docs.cloud.google.com/agent-registry/component-lifecycle-and-discovery.md.txt#discovery-types).

To learn how to manually register A2A-compliant and standard REST agents, see
[Use manual registration for agents](https://docs.cloud.google.com/agent-registry/manual-registration.md.txt).

### Cross-project registration considerations

If your organization uses a centralized governance architecture with
[Agent Gateway](https://docs.cloud.google.com/gemini-enterprise-agent-platform/govern/gateways/agent-gateway-overview.md.txt),
such as the multi-project pattern described in
[Sample deployment patterns](https://docs.cloud.google.com/gemini-enterprise-agent-platform/govern/gateways/set-up-agent-gateway.md.txt#deployment-patterns),
you can deploy a gateway in
[Agent-to-Anywhere egress mode](https://docs.cloud.google.com/gemini-enterprise-agent-platform/govern/gateways/agent-gateway-overview.md.txt#modes)
in a central [governance project](https://docs.cloud.google.com/agent-registry/overview.md.txt#governance-project)
where Agent Registry is enabled, while deploying agents in separate
Google Cloud projects.

If you configure a
[management boundary](https://docs.cloud.google.com/agent-registry/boundaries-and-topology.md.txt),
Agent Registry automatically aggregates supported agents from member projects
into your
[management project](https://docs.cloud.google.com/agent-registry/boundaries-and-topology.md.txt#management-project).

Without a management boundary, automatic registration only discovers resources
in the governance project where Agent Registry is enabled. To let a central
gateway locate and govern remote agents in other Google Cloud projects,
you must manually register each remote agent in the central governance project's
registry. For instructions, see
[Register an agent from another project](https://docs.cloud.google.com/agent-registry/manual-registration.md.txt#cross-project).

## Integrate standalone skills

Agent Registry lets you manage and govern standalone
[skills](https://docs.cloud.google.com/agent-registry/skills-architecture.md.txt) for agents as top-level resources.
Standalone skills are registered as `Skill` resources in your registry,
letting administrators apply fine-grained access policies and manage version
history using
[skill revisions](https://docs.cloud.google.com/agent-registry/skills-architecture.md.txt#skill-revision).

When
[building and managing agents in Gemini Enterprise](https://docs.cloud.google.com/gemini-enterprise-agent-platform/build/managed-agents.md.txt),
you can reference these registered standalone skills to extend your
Gemini Enterprise agent's capabilities.
For information on how to register and manage standalone skills, see
[Register skills](https://docs.cloud.google.com/agent-registry/register-skills.md.txt) and
[Manage skills](https://docs.cloud.google.com/agent-registry/manage-skills.md.txt).