"""MCP Apps: a tool bound to a `ui://` resource the host renders as an interactive surface.
`Apps` is an opt-in `Extension` passed to `MCPServer(extensions=[...])`. The
`@apps.tool(resource_uri=...)` decorator stamps `_meta.ui.resourceUri` onto the
tool; `add_html_resource` registers the matching `ui://` HTML resource. The tool
degrades gracefully: `client_supports_apps(ctx)` reports whether the client
negotiated Apps, so it returns text-only output otherwise.
"""
from mcp.server.apps import Apps, client_supports_apps
from mcp.server.mcpserver import MCPServer
from mcp.server.mcpserver.context import Context
from stories._hosting import run_server_from_args
RESOURCE_URI = "ui://get-time/app.html"
CLOCK_HTML = """
Current time
…
"""
def build_server() -> MCPServer:
apps = Apps()
@apps.tool(resource_uri=RESOURCE_URI, title="Get Time", description="Return the current time.")
def get_time(ctx: Context) -> str:
now = "2026-06-26T00:00:00Z"
if not client_supports_apps(ctx):
return f"The time is {now}."
return now
apps.add_html_resource(RESOURCE_URI, CLOCK_HTML, title="Clock")
return MCPServer("apps-example", extensions=[apps])
if __name__ == "__main__":
run_server_from_args(build_server)