diff --git a/src/google/adk/cli/cli_tools_click.py b/src/google/adk/cli/cli_tools_click.py
index 13a0a620a..1b708fbf6 100644
--- a/src/google/adk/cli/cli_tools_click.py
+++ b/src/google/adk/cli/cli_tools_click.py
@@ -23,6 +23,7 @@
 import os
 import tempfile
 from typing import Optional
+from urllib.parse import urlparse
 
 import click
 from click.core import ParameterSource
@@ -616,18 +617,12 @@ def fast_api_common_options():
 
   def decorator(func):
     @click.option(
-        "--host",
+        "--base_url",
         type=str,
-        help="Optional. The binding host of the server",
-        default="127.0.0.1",
+        help="Optional. The base URL of the server.",
+        default="http://127.0.0.1:8000",
         show_default=True,
     )
-    @click.option(
-        "--port",
-        type=int,
-        help="Optional. The port of the server",
-        default=8000,
-    )
     @click.option(
         "--allow_origins",
         help="Optional. Any additional origins to allow for CORS.",
@@ -719,8 +714,7 @@ def cli_web(
     eval_storage_uri: Optional[str] = None,
     log_level: str = "INFO",
     allow_origins: Optional[list[str]] = None,
-    host: str = "127.0.0.1",
-    port: int = 8000,
+    base_url="http://127.0.0.1:8000",
     trace_to_cloud: bool = False,
     reload: bool = True,
     session_service_uri: Optional[str] = None,
@@ -741,6 +735,9 @@ def cli_web(
     adk web --session_service_uri=[uri] --port=[port] path/to/agents_dir
   """
   logs.setup_adk_logger(getattr(logging, log_level.upper()))
+  parsed_url = urlparse(base_url)
+  host = parsed_url.hostname
+  port = parsed_url.port
 
   @asynccontextmanager
   async def _lifespan(app: FastAPI):
@@ -777,8 +774,7 @@ async def _lifespan(app: FastAPI):
       trace_to_cloud=trace_to_cloud,
       lifespan=_lifespan,
       a2a=a2a,
-      host=host,
-      port=port,
+      base_url=base_url,
       reload_agents=reload_agents,
   )
   config = uvicorn.Config(
@@ -810,8 +806,7 @@ def cli_api_server(
     eval_storage_uri: Optional[str] = None,
     log_level: str = "INFO",
     allow_origins: Optional[list[str]] = None,
-    host: str = "127.0.0.1",
-    port: int = 8000,
+    base_url="http://127.0.0.1:8000",
     trace_to_cloud: bool = False,
     reload: bool = True,
     session_service_uri: Optional[str] = None,
@@ -833,6 +828,9 @@ def cli_api_server(
   """
   logs.setup_adk_logger(getattr(logging, log_level.upper()))
 
+  parsed_url = urlparse(base_url)
+  host = parsed_url.hostname
+  port = parsed_url.port
   session_service_uri = session_service_uri or session_db_url
   artifact_service_uri = artifact_service_uri or artifact_storage_uri
   config = uvicorn.Config(
@@ -846,8 +844,7 @@ def cli_api_server(
           web=False,
           trace_to_cloud=trace_to_cloud,
           a2a=a2a,
-          host=host,
-          port=port,
+          base_url=base_url,
           reload_agents=reload_agents,
       ),
       host=host,
diff --git a/src/google/adk/cli/fast_api.py b/src/google/adk/cli/fast_api.py
index 7d93b5436..0b4a41968 100644
--- a/src/google/adk/cli/fast_api.py
+++ b/src/google/adk/cli/fast_api.py
@@ -64,8 +64,7 @@ def get_fast_api_app(
     allow_origins: Optional[list[str]] = None,
     web: bool,
     a2a: bool = False,
-    host: str = "127.0.0.1",
-    port: int = 8000,
+    base_url: str = "http://127.0.0.1:8000",
     trace_to_cloud: bool = False,
     reload_agents: bool = False,
     lifespan: Optional[Lifespan[FastAPI]] = None,
@@ -352,6 +351,8 @@ async def _get_a2a_runner_async() -> Runner:
         logger.info("Setting up A2A agent: %s", app_name)
 
         try:
+          a2a_rpc_path = f"{base_url}/a2a/{app_name}"
+
           agent_executor = A2aAgentExecutor(
               runner=create_a2a_runner_loader(app_name),
           )
@@ -363,6 +364,8 @@ async def _get_a2a_runner_async() -> Runner:
           with (p / "agent.json").open("r", encoding="utf-8") as f:
             data = json.load(f)
             agent_card = AgentCard(**data)
+            # todo: if url is not defined, override it here
+            agent_card.url = a2a_rpc_path
 
           a2a_app = A2AStarletteApplication(
               agent_card=agent_card,
diff --git a/tests/unittests/cli/test_fast_api.py b/tests/unittests/cli/test_fast_api.py
index f1c9e9d6e..c9be32c1f 100755
--- a/tests/unittests/cli/test_fast_api.py
+++ b/tests/unittests/cli/test_fast_api.py
@@ -432,8 +432,7 @@ def test_app(
         memory_service_uri="",
         allow_origins=["*"],
         a2a=False,  # Disable A2A for most tests
-        host="127.0.0.1",
-        port=8000,
+        base_url="http://127.0.0.1:8000",
     )
 
     # Create a TestClient that doesn't start a real server
@@ -607,8 +606,7 @@ def test_app_with_a2a(
           memory_service_uri="",
           allow_origins=["*"],
           a2a=True,
-          host="127.0.0.1",
-          port=8000,
+          base_url="http://127.0.0.1:8000",
       )
 
       client = TestClient(app)