refactor: extract mcp client creation logic to a separate method

PiperOrigin-RevId: 780609120

src/google/adk/tools/mcp_tool/mcp_session_manager.py

@@ -251,6 +251,49 @@ class MCPSessionManager:
     """
     return session._read_stream._closed or session._write_stream._closed
 
+  def _create_client(self, merged_headers: Optional[Dict[str, str]] = None):
+    """Creates an MCP client based on the connection parameters.
+
+    Args:
+        merged_headers: Optional headers to include in the connection.
+                       Only applicable for SSE and StreamableHTTP connections.
+
+    Returns:
+        The appropriate MCP client instance.
+
+    Raises:
+        ValueError: If the connection parameters are not supported.
+    """
+    if isinstance(self._connection_params, StdioConnectionParams):
+      client = stdio_client(
+          server=self._connection_params.server_params,
+          errlog=self._errlog,
+      )
+    elif isinstance(self._connection_params, SseConnectionParams):
+      client = sse_client(
+          url=self._connection_params.url,
+          headers=merged_headers,
+          timeout=self._connection_params.timeout,
+          sse_read_timeout=self._connection_params.sse_read_timeout,
+      )
+    elif isinstance(self._connection_params, StreamableHTTPConnectionParams):
+      client = streamablehttp_client(
+          url=self._connection_params.url,
+          headers=merged_headers,
+          timeout=timedelta(seconds=self._connection_params.timeout),
+          sse_read_timeout=timedelta(
+              seconds=self._connection_params.sse_read_timeout
+          ),
+          terminate_on_close=self._connection_params.terminate_on_close,
+      )
+    else:
+      raise ValueError(
+          'Unable to initialize connection. Connection should be'
+          ' StdioServerParameters or SseServerParams, but got'
+          f' {self._connection_params}'
+      )
+    return client
+
   async def create_session(
       self, headers: Optional[Dict[str, str]] = None
   ) -> ClientSession:
@@ -298,36 +341,7 @@ class MCPSessionManager:
       exit_stack = AsyncExitStack()
 
       try:
-        if isinstance(self._connection_params, StdioConnectionParams):
-          client = stdio_client(
-              server=self._connection_params.server_params,
-              errlog=self._errlog,
-          )
-        elif isinstance(self._connection_params, SseConnectionParams):
-          client = sse_client(
-              url=self._connection_params.url,
-              headers=merged_headers,
-              timeout=self._connection_params.timeout,
-              sse_read_timeout=self._connection_params.sse_read_timeout,
-          )
-        elif isinstance(
-            self._connection_params, StreamableHTTPConnectionParams
-        ):
-          client = streamablehttp_client(
-              url=self._connection_params.url,
-              headers=merged_headers,
-              timeout=timedelta(seconds=self._connection_params.timeout),
-              sse_read_timeout=timedelta(
-                  seconds=self._connection_params.sse_read_timeout
-              ),
-              terminate_on_close=self._connection_params.terminate_on_close,
-          )
-        else:
-          raise ValueError(
-              'Unable to initialize connection. Connection should be'
-              ' StdioServerParameters or SseServerParams, but got'
-              f' {self._connection_params}'
-          )
+        client = self._create_client(merged_headers)
 
         transports = await exit_stack.enter_async_context(client)
         # The streamable http client returns a GetSessionCallback in addition to the read/write MemoryObjectStreams