Update MCP to reconnect to the server on demand (#141215)

* Reconnect to the MCP client on deman

* Remove debug log

* Update log messages

homeassistant/components/mcp/__init__.py

@@ -39,7 +39,6 @@ async def async_setup_entry(
     entry.async_on_unload(unsub)
 
     entry.runtime_data = coordinator
-    entry.async_on_unload(coordinator.close)
 
     return True
 

homeassistant/components/mcp/coordinator.py

@@ -40,6 +40,7 @@ async def mcp_client(url: str) -> AsyncGenerator[ClientSession]:
             await session.initialize()
             yield session
     except ExceptionGroup as err:
+        _LOGGER.debug("Error creating MCP client: %s", err)
         raise err.exceptions[0] from err
 
 
@@ -51,13 +52,13 @@ class ModelContextProtocolTool(llm.Tool):
         name: str,
         description: str | None,
         parameters: vol.Schema,
-        session: ClientSession,
+        server_url: str,
     ) -> None:
         """Initialize the tool."""
         self.name = name
         self.description = description
         self.parameters = parameters
-        self.session = session
+        self.server_url = server_url
 
     async def async_call(
         self,
@@ -67,10 +68,16 @@ class ModelContextProtocolTool(llm.Tool):
     ) -> JsonObjectType:
         """Call the tool."""
         try:
-            result = await self.session.call_tool(
-                tool_input.tool_name, tool_input.tool_args
-            )
+            async with asyncio.timeout(TIMEOUT):
+                async with mcp_client(self.server_url) as session:
+                    result = await session.call_tool(
+                        tool_input.tool_name, tool_input.tool_args
+                    )
+        except TimeoutError as error:
+            _LOGGER.debug("Timeout when calling tool: %s", error)
+            raise HomeAssistantError(f"Timeout when calling tool: {error}") from error
         except httpx.HTTPStatusError as error:
+            _LOGGER.debug("Error when calling tool: %s", error)
             raise HomeAssistantError(f"Error when calling tool: {error}") from error
         return result.model_dump(exclude_unset=True, exclude_none=True)
 
@@ -79,8 +86,6 @@ class ModelContextProtocolCoordinator(DataUpdateCoordinator[list[llm.Tool]]):
     """Define an object to hold MCP data."""
 
     config_entry: ConfigEntry
-    _session: ClientSession | None = None
-    _setup_error: Exception | None = None
 
     def __init__(self, hass: HomeAssistant, config_entry: ConfigEntry) -> None:
         """Initialize ModelContextProtocolCoordinator."""
@@ -91,52 +96,6 @@ class ModelContextProtocolCoordinator(DataUpdateCoordinator[list[llm.Tool]]):
             config_entry=config_entry,
             update_interval=UPDATE_INTERVAL,
         )
-        self._stop = asyncio.Event()
-
-    async def _async_setup(self) -> None:
-        """Set up the client connection."""
-        connected = asyncio.Event()
-        stop = asyncio.Event()
-        self.config_entry.async_create_background_task(
-            self.hass, self._connect(connected, stop), "mcp-client"
-        )
-        try:
-            async with asyncio.timeout(TIMEOUT):
-                await connected.wait()
-                self._stop = stop
-        finally:
-            if self._setup_error is not None:
-                raise self._setup_error
-
-    async def _connect(self, connected: asyncio.Event, stop: asyncio.Event) -> None:
-        """Create a server-sent event MCP client."""
-        url = self.config_entry.data[CONF_URL]
-        try:
-            async with (
-                sse_client(url=url) as streams,
-                ClientSession(*streams) as session,
-            ):
-                await session.initialize()
-                self._session = session
-                connected.set()
-                await stop.wait()
-        except httpx.HTTPStatusError as err:
-            self._setup_error = err
-            _LOGGER.debug("Error connecting to MCP server: %s", err)
-            raise UpdateFailed(f"Error connecting to MCP server: {err}") from err
-        except ExceptionGroup as err:
-            self._setup_error = err.exceptions[0]
-            _LOGGER.debug("Error connecting to MCP server: %s", err)
-            raise UpdateFailed(
-                "Error connecting to MCP server: {err.exceptions[0]}"
-            ) from err.exceptions[0]
-        finally:
-            self._session = None
-
-    async def close(self) -> None:
-        """Close the client connection."""
-        if self._stop is not None:
-            self._stop.set()
 
     async def _async_update_data(self) -> list[llm.Tool]:
         """Fetch data from API endpoint.
@@ -144,11 +103,15 @@ class ModelContextProtocolCoordinator(DataUpdateCoordinator[list[llm.Tool]]):
         This is the place to pre-process the data to lookup tables
         so entities can quickly look up their data.
         """
-        if self._session is None:
-            raise UpdateFailed("No session available")
         try:
-            result = await self._session.list_tools()
+            async with asyncio.timeout(TIMEOUT):
+                async with mcp_client(self.config_entry.data[CONF_URL]) as session:
+                    result = await session.list_tools()
+        except TimeoutError as error:
+            _LOGGER.debug("Timeout when listing tools: %s", error)
+            raise UpdateFailed(f"Timeout when listing tools: {error}") from error
         except httpx.HTTPError as err:
+            _LOGGER.debug("Error communicating with API: %s", err)
             raise UpdateFailed(f"Error communicating with API: {err}") from err
 
         _LOGGER.debug("Received tools: %s", result.tools)
@@ -165,7 +128,7 @@ class ModelContextProtocolCoordinator(DataUpdateCoordinator[list[llm.Tool]]):
                     tool.name,
                     tool.description,
                     parameters,
-                    self._session,
+                    self.config_entry.data[CONF_URL],
                 )
             )
         return tools