Update capabilities handling and test cases for tools, prompts, and resources

Signed-off-by: edmondfrank <[email protected]>

Author: EdmondFrank

server/server.go

@@ -210,6 +210,12 @@ func NewMCPServer(
 		version:              version,
 		notificationHandlers: make(map[string]NotificationHandlerFunc),
 		notifications:        make(chan ServerNotification, 100),
+		capabilities: serverCapabilities{
+			tools:     &toolCapabilities{listChanged: true},
+			resources: &resourceCapabilities{subscribe: false, listChanged: true},
+			prompts:   &promptCapabilities{listChanged: true},
+			logging:   false,
+		},
 	}
 
 	for _, opt := range opts {
@@ -319,7 +325,7 @@ func (s *MCPServer) HandleMessage(
 		}
 		return s.handleListResourceTemplates(ctx, baseMessage.ID, request)
 	case "resources/read":
-		if s.capabilities.resources == nil {
+		if !s.capabilities.resources.listChanged {
 			return createErrorResponse(
 				baseMessage.ID,
 				mcp.METHOD_NOT_FOUND,
@@ -353,7 +359,7 @@ func (s *MCPServer) HandleMessage(
 		}
 		return s.handleListPrompts(ctx, baseMessage.ID, request)
 	case "prompts/get":
-		if s.capabilities.prompts == nil {
+		if !s.capabilities.prompts.listChanged {
 			return createErrorResponse(
 				baseMessage.ID,
 				mcp.METHOD_NOT_FOUND,
@@ -387,7 +393,7 @@ func (s *MCPServer) HandleMessage(
 		}
 		return s.handleListTools(ctx, baseMessage.ID, request)
 	case "tools/call":
-		if len(s.tools) == 0 {
+		if !s.capabilities.tools.listChanged || len(s.tools) == 0 {
 			return createErrorResponse(
 				baseMessage.ID,
 				mcp.METHOD_NOT_FOUND,
@@ -523,20 +529,20 @@ func (s *MCPServer) handleInitialize(
 		Subscribe   bool `json:"subscribe,omitempty"`
 		ListChanged bool `json:"listChanged,omitempty"`
 	}{
-		Subscribe:   false,
-		ListChanged: true,
+		Subscribe:   s.capabilities.resources.subscribe,
+		ListChanged: s.capabilities.resources.listChanged,
 	}
 
 	capabilities.Prompts = &struct {
 		ListChanged bool `json:"listChanged,omitempty"`
 	}{
-		ListChanged: true,
+		ListChanged: s.capabilities.prompts.listChanged,
 	}
 
 	capabilities.Tools = &struct {
 		ListChanged bool `json:"listChanged,omitempty"`
 	}{
-		ListChanged: true,
+		ListChanged: s.capabilities.tools.listChanged,
 	}
 
 	if s.capabilities.logging {

server/server_test.go

@@ -55,6 +55,7 @@ func TestMCPServer_Capabilities(t *testing.T) {
 			options: []ServerOption{
 				WithResourceCapabilities(true, true),
 				WithPromptCapabilities(true),
+				WithToolCapabilities(true),
 				WithLogging(),
 			},
 			validate: func(t *testing.T, response mcp.JSONRPCMessage) {
@@ -73,8 +74,8 @@ func TestMCPServer_Capabilities(t *testing.T) {
 				assert.Equal(t, "1.0.0", initResult.ServerInfo.Version)
 
 				assert.NotNil(t, initResult.Capabilities.Resources)
-				// Resources capabilities are now always false for subscribe and true for listChanged
-				assert.False(t, initResult.Capabilities.Resources.Subscribe)
+
+				assert.True(t, initResult.Capabilities.Resources.Subscribe)
 				assert.True(t, initResult.Capabilities.Resources.ListChanged)
 
 				assert.NotNil(t, initResult.Capabilities.Prompts)
@@ -83,6 +84,43 @@ func TestMCPServer_Capabilities(t *testing.T) {
 				assert.NotNil(t, initResult.Capabilities.Tools)
 				assert.True(t, initResult.Capabilities.Tools.ListChanged)
 
+				assert.NotNil(t, initResult.Capabilities.Logging)
+			},
+		},
+		{
+			name: "Specific capabilities",
+			options: []ServerOption{
+				WithResourceCapabilities(true, false),
+				WithPromptCapabilities(true),
+				WithToolCapabilities(false),
+				WithLogging(),
+			},
+			validate: func(t *testing.T, response mcp.JSONRPCMessage) {
+				resp, ok := response.(mcp.JSONRPCResponse)
+				assert.True(t, ok)
+
+				initResult, ok := resp.Result.(mcp.InitializeResult)
+				assert.True(t, ok)
+
+				assert.Equal(
+					t,
+					mcp.LATEST_PROTOCOL_VERSION,
+					initResult.ProtocolVersion,
+				)
+				assert.Equal(t, "test-server", initResult.ServerInfo.Name)
+				assert.Equal(t, "1.0.0", initResult.ServerInfo.Version)
+
+				assert.NotNil(t, initResult.Capabilities.Resources)
+
+				assert.True(t, initResult.Capabilities.Resources.Subscribe)
+				assert.False(t, initResult.Capabilities.Resources.ListChanged)
+
+				assert.NotNil(t, initResult.Capabilities.Prompts)
+				assert.True(t, initResult.Capabilities.Prompts.ListChanged)
+
+				assert.NotNil(t, initResult.Capabilities.Tools)
+				assert.False(t, initResult.Capabilities.Tools.ListChanged)
+
 				assert.NotNil(t, initResult.Capabilities.Logging)
 			},
 		},
@@ -600,14 +638,10 @@ func TestMCPServer_HandleUndefinedHandlers(t *testing.T) {
 }
 
 func TestMCPServer_HandleMethodsWithoutCapabilities(t *testing.T) {
-	server := NewMCPServer(
-		"test-server",
-		"1.0.0",
-	)
-
 	tests := []struct {
 		name        string
 		message     string
+		options  []ServerOption
 		expectedErr int
 	}{
 		{
@@ -620,6 +654,9 @@ func TestMCPServer_HandleMethodsWithoutCapabilities(t *testing.T) {
                         "name": "test-tool"
                     }
                 }`,
+			options: []ServerOption{
+				WithToolCapabilities(false),
+			},
 			expectedErr: mcp.METHOD_NOT_FOUND,
 		},
 		{
@@ -632,6 +669,9 @@ func TestMCPServer_HandleMethodsWithoutCapabilities(t *testing.T) {
                         "name": "test-prompt"
                     }
                 }`,
+			options: []ServerOption{
+				WithPromptCapabilities(false),
+			},
 			expectedErr: mcp.METHOD_NOT_FOUND,
 		},
 		{
@@ -644,12 +684,16 @@ func TestMCPServer_HandleMethodsWithoutCapabilities(t *testing.T) {
                         "uri": "test-resource"
                     }
                 }`,
+			options: []ServerOption{
+				WithResourceCapabilities(false, false),
+			},
 			expectedErr: mcp.METHOD_NOT_FOUND,
 		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			server := NewMCPServer("test-server", "1.0.0", tt.options...)
 			response := server.HandleMessage(
 				context.Background(),
 				[]byte(tt.message),