feat: add a2a agent card generation with the CLI

pyproject.toml

@@ -211,6 +211,7 @@ known_third_party = ["google.adk"]
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
+pythonpath = "src"
 asyncio_default_fixture_loop_scope = "function"
 asyncio_mode = "auto"
 

src/google/adk/cli/cli.py

@@ -33,6 +33,7 @@
 from ..sessions.session import Session
 from ..utils.context_utils import Aclosing
 from ..utils.env_utils import is_env_enabled
+from .cli_generate_agent_card import generate_agent_card
 from .service_registry import load_services_module
 from .utils import envs
 from .utils.agent_loader import AgentLoader

src/google/adk/cli/cli_generate_agent_card.py

@@ -0,0 +1,97 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import annotations
+
+import asyncio
+import json
+import os
+
+import click
+
+from .utils.agent_loader import AgentLoader
+
+
+@click.command(name="generate_agent_card")
+@click.option(
+    "--protocol",
+    default="https",
+    help="Protocol for the agent URL (default: https)",
+)
+@click.option(
+    "--host",
+    default="127.0.0.1",
+    help="Host for the agent URL (default: 127.0.0.1)",
+)
+@click.option(
+    "--port",
+    default="8000",
+    help="Port for the agent URL (default: 8000)",
+)
+@click.option(
+    "--create-file",
+    is_flag=True,
+    default=False,
+    help="Create agent.json file in each agent directory",
+)
+def generate_agent_card(
+    protocol: str, host: str, port: str, create_file: bool
+) -> None:
+  """Generates agent cards for all detected agents."""
+  asyncio.run(_generate_agent_card_async(protocol, host, port, create_file))
+
+
+async def _generate_agent_card_async(
+    protocol: str, host: str, port: str, create_file: bool
+) -> None:
+  try:
+    from ..a2a.utils.agent_card_builder import AgentCardBuilder
+  except ImportError:
+    click.secho(
+        "Error: 'a2a' package is required for this command. "
+        "Please install it with 'pip install google-adk[a2a]'.",
+        fg="red",
+        err=True,
+    )
+    raise click.Abort()
+
+  cwd = os.getcwd()
+  loader = AgentLoader(agents_dir=cwd)
+  agent_names = loader.list_agents()
+  agent_cards = []
+
+  for agent_name in agent_names:
+    try:
+      agent = loader.load_agent(agent_name)
+      # If it's an App, get the root agent
+      if hasattr(agent, "root_agent"):
+        agent = agent.root_agent
+      builder = AgentCardBuilder(
+          agent=agent,
+          rpc_url=f"{protocol}://{host}:{port}/{agent_name}",
+      )
+      card = await builder.build()
+      card_dict = card.model_dump(exclude_none=True)
+      agent_cards.append(card_dict)
+
+      if create_file:
+        agent_dir = os.path.join(cwd, agent_name)
+        agent_json_path = os.path.join(agent_dir, "agent.json")
+        with open(agent_json_path, "w", encoding="utf-8") as f:
+          json.dump(card_dict, f, indent=2)
+    except Exception as e:
+      # Log error but continue with other agents
+      # Using click.echo to print to stderr to not mess up JSON output on stdout
+      click.echo(f"Error processing agent {agent_name}: {e}", err=True)
+
+  click.echo(json.dumps(agent_cards, indent=2))

src/google/adk/cli/cli_tools_click.py

@@ -38,6 +38,8 @@
 from ..evaluation.constants import MISSING_EVAL_DEPENDENCIES_MESSAGE
 from ..features import FeatureName
 from ..features import override_feature_enabled
+from ..sessions.migration import migration_runner
+from .cli import generate_agent_card
 from .cli import run_cli
 from .fast_api import get_fast_api_app
 from .utils import envs
@@ -2111,3 +2113,6 @@ def cli_deploy_gke(
     )
   except Exception as e:
     click.secho(f"Deploy failed: {e}", fg="red", err=True)
+
+
+main.add_command(generate_agent_card)