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.
MCP client-capabilities header gains a discover-protocol-version companion header
claude.ai MCP calls now send a discover-protocol-version header whenever the discovery mode isn't off.
Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
MCPArea: what it touches
Internal ChangesKind: in v2.1.259,
Internal ChangesSection of the release