diff --git a/server.go b/server.go
index 55295fda..714f7542 100644
--- a/server.go
+++ b/server.go
@@ -96,7 +96,7 @@ type options struct {
 	maxConcurrentStreams uint32
 }
 
-// ServerOption sets options.
+// A ServerOption sets options.
 type ServerOption func(*options)
 
 // MaxConcurrentStreams returns an Option that will apply a limit on the number
@@ -312,7 +312,7 @@ func (s *Server) handleStream(t transport.ServerTransport, stream *transport.Str
 	t.WriteStatus(stream, codes.Unimplemented, fmt.Sprintf("unknown method %v", method))
 }
 
-// Stop stops the gRPC server. Once it returns, the server stops accepting
+// Stop stops the gRPC server. Once Stop returns, the server stops accepting
 // connection requests and closes all the connected connections.
 func (s *Server) Stop() {
 	s.mu.Lock()
@@ -329,9 +329,9 @@ func (s *Server) Stop() {
 	}
 }
 
-// CloseConns closes all exiting transports but keeps s.lis accepting new
+// TestingCloseConns closes all exiting transports but keeps s.lis accepting new
 // connections. This is for test only now.
-func (s *Server) CloseConns() {
+func (s *Server) TestingCloseConns() {
 	s.mu.Lock()
 	for c := range s.conns {
 		c.Close()
diff --git a/stream.go b/stream.go
index 73681e9e..53baacac 100644
--- a/stream.go
+++ b/stream.go
@@ -47,12 +47,17 @@ import (
 type Stream interface {
 	// Context returns the context for this stream.
 	Context() context.Context
-	// SendProto blocks until it sends a proto message out or some
-	// error happens.
-	SendProto(proto.Message) error
-	// RecvProto blocks until either a proto message is received or some
-	// error happens.
-	RecvProto(proto.Message) error
+	// SendProto blocks until it sends m, the stream is done or the stream
+	// breaks.
+	// On error, it aborts the stream and returns an RPC status on client
+	// side. On server side, it simply returns the error to the caller.
+	// SendProto is called by generated code.
+	SendProto(m proto.Message) error
+	// RecvProto blocks until it receives a proto message or the stream is
+	// done. On client side, it returns io.EOF when the stream is done. On
+	// any other error, it aborts the streama nd returns an RPC status. On
+	// server side, it simply returns the error to the caller.
+	RecvProto(m proto.Message) error
 }
 
 // ClientStream defines the interface a client stream has to satify.
@@ -64,9 +69,11 @@ type ClientStream interface {
 	// after stream.Recv() returns non-nil error (including io.EOF) for
 	// bi-directional streaming and server streaming or stream.CloseAndRecv()
 	// returns for client streaming in order to receive trailer metadata if
-	// present.
+	// present. Otherwise, it could returns an empty MD even though trailer
+	// is present.
 	Trailer() metadata.MD
-	// CloseSend closes the send direction of the stream.
+	// CloseSend closes the send direction of the stream. It closes the stream
+	// when non-nil error is met.
 	CloseSend() error
 	Stream
 }
@@ -101,29 +108,18 @@ type clientStream struct {
 	p *parser
 }
 
-// Context returns the clientStream's associated context.
 func (cs *clientStream) Context() context.Context {
 	return cs.s.Context()
 }
 
-// Header returns the header metedata received from the server if there
-// is any. Empty metadata.MD is returned if there is no header metadata.
-// It blocks if the metadata is not ready to read.
 func (cs *clientStream) Header() (md metadata.MD, err error) {
 	return cs.s.Header()
 }
 
-// Trailer returns the trailer metadata from the server. It must be called
-// after stream.Recv() returns non-nil error (including io.EOF) for
-// bi-directional streaming and server streaming or stream.CloseAndRecv()
-// returns for client streaming in order to receive trailer metadata if
-// present.
 func (cs *clientStream) Trailer() metadata.MD {
 	return cs.s.Trailer()
 }
 
-// SendProto blocks until m is sent out or an error happens. It closes the
-// stream when a non-nil error is met. This is called by generated code.
 func (cs *clientStream) SendProto(m proto.Message) (err error) {
 	defer func() {
 		if err == nil || err == io.EOF {
@@ -141,10 +137,6 @@ func (cs *clientStream) SendProto(m proto.Message) (err error) {
 	return cs.t.Write(cs.s, out, &transport.Options{Last: false})
 }
 
-// RecvProto blocks until it receives a proto message or an error happens.
-// When an non-nil error (including EOF which indicates the success of an
-// RPC) is met, it also closes the stream and returns the RPC status to
-// the caller. This is called by generated code.
 func (cs *clientStream) RecvProto(m proto.Message) (err error) {
 	err = recvProto(cs.p, m)
 	if err == nil {
@@ -163,8 +155,6 @@ func (cs *clientStream) RecvProto(m proto.Message) (err error) {
 	return toRPCErr(err)
 }
 
-// CloseSend closes the send direction of the stream. It closes the stream
-// when non-nil error is met.
 func (cs *clientStream) CloseSend() (err error) {
 	err = cs.t.Write(cs.s, nil, &transport.Options{Last: true})
 	if err == nil || err == io.EOF {
@@ -180,7 +170,8 @@ func (cs *clientStream) CloseSend() (err error) {
 // ServerStream defines the interface a server stream has to satisfy.
 type ServerStream interface {
 	// SendHeader sends the header metadata. It should not be called
-	// after SendProto.
+	// after SendProto. It fails if called multiple times or if
+	// called after SendProto.
 	SendHeader(metadata.MD) error
 	// SetTrailer sets the trailer metadata which will be sent with the
 	// RPC status.
@@ -197,20 +188,14 @@ type serverStream struct {
 	statusDesc string
 }
 
-// Context returns the associated context so that server applications can
-// manipulate it.
 func (ss *serverStream) Context() context.Context {
 	return ss.s.Context()
 }
 
-// SendHeader sends header metadata. It fails if called multiple times or if
-// called after SendProto.
 func (ss *serverStream) SendHeader(md metadata.MD) error {
 	return ss.t.WriteHeader(ss.s, md)
 }
 
-// SetTrailer sends trailer metadata. The metadata will be sent with the final
-// RPC status.
 func (ss *serverStream) SetTrailer(md metadata.MD) {
 	if md.Len() == 0 {
 		return
@@ -219,8 +204,6 @@ func (ss *serverStream) SetTrailer(md metadata.MD) {
 	return
 }
 
-// SendProto blocks until m is sent out or an error is met. This is called by
-// generated code.
 func (ss *serverStream) SendProto(m proto.Message) error {
 	out, err := encode(m, compressionNone)
 	if err != nil {
@@ -230,8 +213,6 @@ func (ss *serverStream) SendProto(m proto.Message) error {
 	return ss.t.Write(ss.s, out, &transport.Options{Last: false})
 }
 
-// RecvProto blocks until it receives a message or an error is met. This is
-// called by generated code.
 func (ss *serverStream) RecvProto(m proto.Message) error {
 	return recvProto(ss.p, m)
 }
diff --git a/test/end2end_test.go b/test/end2end_test.go
index 75eb8622..b0951454 100644
--- a/test/end2end_test.go
+++ b/test/end2end_test.go
@@ -318,7 +318,7 @@ func TestRetry(t *testing.T) {
 		// The server shuts down the network connection to make a
 		// transport error which will be detected by the client side
 		// code.
-		s.CloseConns()
+		s.TestingCloseConns()
 		wg.Done()
 	}()
 	// All these RPCs should succeed eventually.