Under the hood
claude.ai MCP calls now send a discover-protocol-version header whenever the discovery mode isn't off.
Outgoing headers for claude.ai MCP calls now also include an anthropic-mcp-discover-protocol-version header, added when the mode value is not "off". The existing client-capabilities header is now skipped only when both a renamed check and mode === "off" fail, whereas previously it was skipped whenever a single check failed.