Gemini Registration

Requires: A deployed agent. For Agent Runtime in Gemini platform, deployment_metadata.json (created by agents-cli deploy) enables auto-detection. For Cloud Run or GKE, provide the agent card URL and flags directly.

Prerequisites

1. Agent must be deployed — the agent must be running and reachable
2. Gemini app must exist — Create one in the Google Cloud console before registering
3. deployment_metadata.json (Agent Runtime only) — Created automatically by agents-cli deploy; contains the Agent Runtime ID, deployment target, the A2A flag, and the agent directory
4. Text-based agent — Live/voice (bidi) agents are not supported by the Gemini app, which has no /run_live transport. Register a text-based agent instead.

Required Permissions for A2A on Cloud Run

• roles/run.servicesInvoker granted to the Discovery Engine service account (service-<PROJECT_NUMBER>@gcp-sa-discoveryengine.iam.gserviceaccount.com) on the Cloud Run service.

Registration Modes

A2A Registration

Every scaffolded agent serves the Agent-to-Agent protocol. A2A is the default — and only — registration type on Cloud Run and GKE (no reasoning engine to invoke natively). It also works on Agent Runtime via --registration-type a2a. For an ADK agent there the CLI warns against it, because the Gemini app can invoke Agent Runtime natively via :streamQuery — prefer ADK registration in that case. For an agent built on another framework there is no ADK app to invoke natively, so A2A is the right mode on every target and the warning is expected. Pass the agent card URL and the command fetches the card and registers it; display name and description default to the card's name/description.

# A2A on Cloud Run / GKE. The card path depends on the project's language:
#   Python -> /a2a/{app_name}/.well-known/agent-card.json
#   Go     -> /.well-known/agent-card.json
agents-cli publish gemini \
  --agent-card-url https://my-service-abc123.us-east1.run.app/a2a/app/.well-known/agent-card.json \
  --gemini-app-id projects/123456/locations/global/collections/default_collection/engines/my-app

Pass --display-name / --description to override the card defaults. On Agent Runtime, the card URL auto-builds from deployment_metadata.json if you omit --agent-card-url.

ADK Registration (default on Agent Runtime)

ADK projects only. The agent must be deployed to Agent Runtime as an ADK app, since registration invokes it through :streamQuery. An agent on another framework registers over A2A, so deploy it to Cloud Run or GKE and publish from there.

This is the default and recommended registration for ADK agents on Agent Runtime: the Gemini app invokes the agent natively via :streamQuery on its reasoning engine resource, authenticating end-to-end. Under the hood, :streamQuery dispatches to the AdkApp's streaming_agent_run_with_events method — when debugging an ADK invocation, search the runtime's reasoning_engine_stderr logs for that method name to trace the failure. It's also the path to use when the agent needs an OAuth authorization (--authorization-id). The agent is registered directly via its reasoning engine resource name; no agent card URL is needed.

agents-cli publish gemini \
  --registration-type adk \
  --agent-runtime-id projects/123456/locations/us-east1/reasoningEngines/789 \
  --gemini-app-id projects/123456/locations/global/collections/default_collection/engines/my-app \
  --display-name "My Agent" \
  --description "Handles customer queries" \
  --tool-description "Answers questions about products"

Programmatic Mode (CI/CD)

The command is non-interactive by default — pass all required values via flags or environment variables. This makes it safe for CI/CD pipelines.

Via flags

agents-cli publish gemini \
  --agent-runtime-id "$AGENT_RUNTIME_ID" \
  --gemini-app-id "$GEMINI_APP_ID" \
  --display-name "Production Agent" \
  --registration-type adk

Via environment variables

Most flags have an env var alternative (--metadata-file, --interactive, and --list do not):

export AGENT_RUNTIME_ID="projects/123456/locations/us-east1/reasoningEngines/789"
export GEMINI_APP_ID="projects/123456/locations/global/collections/default_collection/engines/my-app"
export GEMINI_DISPLAY_NAME="Production Agent"
export GEMINI_DESCRIPTION="Handles customer queries"

agents-cli publish gemini

Interactive Mode (--interactive)

Pass --interactive (or -i) to be guided through any missing values with interactive prompts. The command will list available Gemini apps, offer to auto-detect the Agent Runtime ID from metadata, and prompt for display name and description.

agents-cli publish gemini --interactive

Complete Flag Reference

The old names still work as hidden aliases: publish gemini-enterprise, --gemini-enterprise-app-id, and the ID / GEMINI_ENTERPRISE_APP_ID env vars. Projects generated by earlier versions call publish gemini-enterprise from make publish-gemini-enterprise; newer Go and Java projects keep that target and add make publish-gemini as an alias.

Auto-Detection from Metadata

When deployment_metadata.json exists, the command automatically:

• Reads the Agent Runtime ID (remote_agent_runtime_id)
• Determines the registration type: defaults to ADK (native :streamQuery) on Agent Runtime, and A2A on Cloud Run / GKE (which have no reasoning engine). A project scaffolded with another framework serves no ADK app, so it defaults to A2A on every target. Override with --registration-type.
• Determines the deployment target for authentication

This means that for the simplest case (an ADK agent on Agent Runtime, registered as ADK), you only need to provide the Gemini app ID:

agents-cli publish gemini \
  --gemini-app-id projects/123456/locations/global/collections/default_collection/engines/my-app

Agent Registry (agents and MCP servers)

Agent Registry (Preview) is the Google Cloud fleet-wide catalog of agents and MCP servers, separate from a Gemini app. Agents deployed to a managed runtime (Agent Runtime in Gemini platform) are auto-registered — no extra step after agents-cli deploy. Manage them with gcloud (requires roles/agentregistry.editor):

# List / inspect agents
gcloud agent-registry agents list --project PROJECT --location LOCATION
gcloud agent-registry agents describe AGENT_NAME

# Update endpoint/metadata — edit the Service resource, not the Agent
gcloud agent-registry services update AGENT_NAME \
  --display-name "..." --description "..." \
  --interfaces "url=ENDPOINT_URL,protocolBinding=http-json"

# Register an external MCP server: not auto-introspected, so upload a
# toolspec.json (its tools/list response, max 10 KB). No us/eu multi-region.
gcloud agent-registry services create SERVER_NAME --location=LOCATION \
  --mcp-server-spec-type=tool-spec --mcp-server-spec-content=toolspec.json \
  --interfaces="url=SERVER_URL,protocolBinding=jsonrpc"  # or http-json, grpc

# Remove: delete the underlying runtime agent (auto-registered) OR, for
# manually registered agents/servers, delete the Service resource
gcloud agent-registry services delete NAME

Terraform: google_agent_registry_service with an mcp_server_spec block.

Docs: https://docs.cloud.google.com/agent-registry/manage-agents · https://docs.cloud.google.com/agent-registry/register-mcp-servers

Troubleshooting

Related Skills

• /google-agents-cli-deploy — Deployment targets, CI/CD pipelines, and production workflows (also covers Agent Gateway governed ingress/egress and Semantic Governance awareness)
• /google-agents-cli-workflow — Development workflow, coding guidelines, and operational rules
• /google-agents-cli-scaffold — Project creation and enhancement with agents-cli scaffold create / scaffold enhance