diff --git a/cmd/signaldctl/cmd/protocol.go b/cmd/signaldctl/cmd/protocol.go
new file mode 100644
index 0000000..5a0db72
--- /dev/null
+++ b/cmd/signaldctl/cmd/protocol.go
@@ -0,0 +1,41 @@
+package cmd
+
+import (
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/spf13/cobra"
+	"gitlab.com/signald/signald-go/cmd/signaldctl/common"
+	"gitlab.com/signald/signald-go/signald"
+)
+
+var protocolCmd = &cobra.Command{
+	Use:   "protocol",
+	Short: "return a machine-readable description of the signald client protocol. Details at https://signald.org/articles/socket-protocol/",
+	RunE: func(cmd *cobra.Command, args []string) error {
+		go common.Signald.Listen(nil)
+
+		req := map[string]string{"version": "v1", "type": "protocol", "id": signald.GenerateID()}
+		err := common.Signald.RawRequest(req)
+		if err != nil {
+			log.Println("signald-go: error submitting request to signald")
+			return err
+		}
+
+		responseChannel := common.Signald.GetResponseListener(req["id"])
+		defer common.Signald.CloseResponseListener(req["id"])
+
+		rawResponse := <-responseChannel
+		if rawResponse.Error != nil {
+			return fmt.Errorf("signald error: %s", string(rawResponse.Error))
+		}
+
+		_, err = os.Stdout.Write(rawResponse.Data)
+		return err
+	},
+}
+
+func init() {
+	RootCmd.AddCommand(protocolCmd)
+}