feat: google/adk-python#479 support for streamable http MCP servers for MCPToolset

Copybara import of the project:

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c5b9d49d7b6d858ff0a93bd690e6d653b7c32221 by Omar BENHAMID <omar.benhamid@smart-gts.com>:

feat: google/adk-python#479 support for streamable http MCP servers for MCPToolset

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9431bc19e6538c1b814aba0b24ff564acf046075 by Omar BENHAMID <omar.benhamid@smart-gts.com>:

feat: google/adk-python#479 streamable http added to right package

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8b4aabed45a6f0dc828beb61f12985dc7b14f3d0 by Omar BENHAMID <omar.benhamid@smart-gts.com>:

feat: google/adk-python#479 streamable http : review feedbacks + sample agent
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/650 from omarbenhamid:feature/mcp-streamable-http 625f028784c216401d45cb1b5d4d998535ebcb00
PiperOrigin-RevId: 764419586

contributing/samples/mcp_streamablehttp_agent/filesystem_server.py

@@ -0,0 +1,80 @@
+# 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.
+
+import asyncio
+import os
+from pathlib import Path
+import sys
+from mcp.server.fastmcp import FastMCP
+
+# Create an MCP server with a name
+mcp = FastMCP("Filesystem Server", host="localhost", port=3000)
+
+
+# Add a tool to read file contents
+@mcp.tool(description="Read contents of a file")
+def read_file(filepath: str) -> str:
+  """Read and return the contents of a file."""
+  with open(filepath, "r") as f:
+    return f.read()
+
+
+# Add a tool to list directory contents
+@mcp.tool(description="List contents of a directory")
+def list_directory(dirpath: str) -> list:
+  """List all files and directories in the given directory."""
+  return os.listdir(dirpath)
+
+
+# Add a tool to get current working directory
+@mcp.tool(description="Get current working directory")
+def get_cwd() -> str:
+  """Return the current working directory."""
+  return str(Path.cwd())
+
+
+# Graceful shutdown handler
+async def shutdown(signal, loop):
+  """Cleanup tasks tied to the service's shutdown."""
+  print(f"\nReceived exit signal {signal.name}...")
+
+  # Get all running tasks
+  tasks = [t for t in asyncio.all_tasks() if t is not asyncio.current_task()]
+
+  # Cancel all tasks
+  for task in tasks:
+    task.cancel()
+
+  print(f"Cancelling {len(tasks)} outstanding tasks")
+  await asyncio.gather(*tasks, return_exceptions=True)
+
+  # Stop the loop
+  loop.stop()
+  print("Shutdown complete!")
+
+
+# Main entry point with graceful shutdown handling
+if __name__ == "__main__":
+  try:
+    # The MCP run function ultimately uses asyncio.run() internally
+    mcp.run(transport="streamable-http")
+  except KeyboardInterrupt:
+    print("\nServer shutting down gracefully...")
+    # The asyncio event loop has already been stopped by the KeyboardInterrupt
+    print("Server has been shut down.")
+  except Exception as e:
+    print(f"Unexpected error: {e}")
+    sys.exit(1)
+  finally:
+    print("Thank you for using the Filesystem MCP Server!")