mcp: add Cacheable fields to DiscoverResult (#1022)

This PR add the Cacheable fields to the DiscoverResult, as it was added
later
(8e4c2322ca)

mcp/protocol.go

@@ -1129,6 +1129,7 @@ func (x *DiscoverParams) SetProgressToken(t any) { setProgressToken(x, t) }
 
 type DiscoverResult struct {
 	Meta `json:"_meta,omitempty"`
+	Cacheable
 	// The versions of the Model Context Protocol that the server supports.
 	SupportedVersions []string `json:"supportedVersions"`
 	// The server's capabilities.

mcp/server.go

@@ -869,12 +869,14 @@ func (s *Server) discover(_ context.Context, req *ServerRequest[*DiscoverParams]
 			ClientInfo:      req.ClientInfo(),
 		}
 	})
-	return &DiscoverResult{
+	res := &DiscoverResult{
 		SupportedVersions: versions,
 		Capabilities:      s.capabilities(),
 		ServerInfo:        s.impl,
 		Instructions:      s.opts.Instructions,
-	}, nil
+	}
+	res.setDefaultCacheableValues()
+	return res, nil
 }
 
 // filterSupportedVersions returns the subset of [supportedProtocolVersions]

mcp/testdata/conformance/server/discover.txtar

@@ -21,6 +21,8 @@ supports, its capabilities, and its identity.
 	"jsonrpc": "2.0",
 	"id": 1,
 	"result": {
+		"ttlMs": 0,
+		"cacheScope": "public",
 		"supportedVersions": [
 			"2026-07-28",
 			"2025-11-25",

mcp/transport_example_test.go

@@ -42,7 +42,7 @@ func ExampleLoggingTransport() {
 	}
 
 	// Output:
-	// read: {"jsonrpc":"2.0","id":1,"result":{"supportedVersions":["2026-07-28","2025-11-25","2025-06-18","2025-03-26","2024-11-05"],"capabilities":{"logging":{}},"serverInfo":{"name":"server","version":"v0.0.1"}}}
+	// read: {"jsonrpc":"2.0","id":1,"result":{"ttlMs":0,"cacheScope":"public","supportedVersions":["2026-07-28","2025-11-25","2025-06-18","2025-03-26","2024-11-05"],"capabilities":{"logging":{}},"serverInfo":{"name":"server","version":"v0.0.1"}}}
 	// write: {"jsonrpc":"2.0","id":1,"method":"server/discover","params":{"_meta":{"io.modelcontextprotocol/clientCapabilities":{"roots":{"listChanged":true}},"io.modelcontextprotocol/clientInfo":{"name":"client","version":"v0.0.1"},"io.modelcontextprotocol/protocolVersion":"2026-07-28"}}}
 }