all: minor cleanup (#545)

Also fix a flaky test case in TestStreamableServerTransport.

docs/client.md

@@ -145,7 +145,7 @@ func Example_elicitation() {
 	}
 	defer ss.Close()
 
-	c := mcp.NewClient(testImpl, &mcp.ClientOptions{
+	c := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, &mcp.ClientOptions{
 		ElicitationHandler: func(context.Context, *mcp.ElicitRequest) (*mcp.ElicitResult, error) {
 			return &mcp.ElicitResult{Action: "accept", Content: map[string]any{"test": "value"}}, nil
 		},

mcp/client_example_test.go

@@ -112,7 +112,7 @@ func Example_elicitation() {
 	}
 	defer ss.Close()
 
-	c := mcp.NewClient(testImpl, &mcp.ClientOptions{
+	c := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, &mcp.ClientOptions{
 		ElicitationHandler: func(context.Context, *mcp.ElicitRequest) (*mcp.ElicitResult, error) {
 			return &mcp.ElicitResult{Action: "accept", Content: map[string]any{"test": "value"}}, nil
 		},

mcp/server.go

@@ -380,7 +380,7 @@ func setSchema[T any](sfield *any, rfield **jsonschema.Resolved) (zero any, err
 // If the tool's input schema is nil, it is set to the schema inferred from the
 // In type parameter. Types are inferred from Go types, and property
 // descriptions are read from the 'jsonschema' struct tag. Internally, the SDK
-// uses the github.com/google/jsonschema-go package for ineference and
+// uses the github.com/google/jsonschema-go package for inference and
 // validation. The In type argument must be a map or a struct, so that its
 // inferred JSON Schema has type "object", as required by the spec. As a
 // special case, if the In type is 'any', the tool's input schema is set to an
@@ -498,6 +498,9 @@ func (s *Server) changeAndNotify(notification string, params Params, change func
 }
 
 // Sessions returns an iterator that yields the current set of server sessions.
+//
+// There is no guarantee that the iterator observes sessions that are added or
+// removed during iteration.
 func (s *Server) Sessions() iter.Seq[*ServerSession] {
 	s.mu.Lock()
 	clients := slices.Clone(s.sessions)

mcp/streamable_test.go

@@ -675,13 +675,14 @@ func TestStreamableServerTransport(t *testing.T) {
 					headers: http.Header{"MCP-Protocol-Version": {"2025-03-26"}},
 					// Two messages => batch. Expect OK with two responses in order.
 					messages: []jsonrpc.Message{
+						// Note: only include one request here, because responses are not
+						// necessarily sorted.
 						req(201, "tools/call", &CallToolParams{Name: "tool"}),
-						req(202, "tools/call", &CallToolParams{Name: "tool"}),
+						req(0, "notifications/roots/list_changed", &RootsListChangedParams{}),
 					},
 					wantStatusCode: http.StatusOK,
 					wantMessages: []jsonrpc.Message{
 						resp(201, &CallToolResult{Content: []Content{}}, nil),
-						resp(202, &CallToolResult{Content: []Content{}}, nil),
 					},
 				},
 			},

mcp/transport.go

@@ -104,8 +104,12 @@ func (t *InMemoryTransport) Connect(context.Context) (Connection, error) {
 	return newIOConn(t.rwc), nil
 }
 
-// NewInMemoryTransports returns two [InMemoryTransports] that connect to each
+// NewInMemoryTransports returns two [InMemoryTransport] objects that connect
-// other.
+// to each other.
+//
+// The resulting transports are symmetrical: use either to connect to a server,
+// and then the other to connect to a client. Servers must be connected before
+// clients, as the client initializes the MCP session during connection.
 func NewInMemoryTransports() (*InMemoryTransport, *InMemoryTransport) {
 	c1, c2 := net.Pipe()
 	return &InMemoryTransport{c1}, &InMemoryTransport{c2}