MCP Server Card (SEP-2127 discovery document)

The Server Card from SEP-2127 "MCP Server Cards - HTTP Server Discovery": one small JSON document that says who operates this MCP server, where its endpoint is, which protocol revisions it speaks, and how a client authenticates. It is served at the SEP's reserved location, the streamable-HTTP URL plus /server-card, and it deliberately lists no tools - the specification reserves that for tools/list.

Public, no authentication. Readable from any browser origin. Carries an ETag; send If-None-Match to receive 304 Not Modified. The same bytes are also served at /.well-known/mcp.json, /.well-known/mcp and /.well-known/mcp/server-card.json, the paths some directory crawlers request by convention. The domain-level index that points here is /.well-known/ai-catalog.json.

Every field is rendered from the same values as /mcp/health and the server/discover result, so the three cannot disagree.