MCP Client quickstart implicitly assumes single tool calls in responses

[ciccolo-anthropic]

Describe the bug
The code in this section: https://github.com/modelcontextprotocol/docs/blob/main/quickstart/client.mdx#query-processing-logic

Will silently fail if the response contains multiple tool calls.

Expected behavior
The code should either properly handle multiple tool calls or indicate that it doesn't.