tool annotations

Author: lkingland

pkg/mcp/tools.go

@@ -105,6 +105,12 @@ func appendBoolFlag(args []string, flag string, value *bool) []string {
 	return args
 }
 
+// ptr returns a pointer to the given value.
+// Useful for setting optional annotation fields.
+func ptr[T any](v T) *T {
+	return &v
+}
+
 // healthCheck is a simple tool for testing MCP server connectivity
 type healthCheck struct{}
 

pkg/mcp/tools_build.go

@@ -37,6 +37,12 @@ func (t buildTool) desc() *mcp.Tool {
 		Name:        "build",
 		Title:       "Build Function",
 		Description: "Build the Function's container image in the current directory.",
+		Annotations: &mcp.ToolAnnotations{
+			Title:           "Build Function",
+			ReadOnlyHint:    false,
+			DestructiveHint: ptr(false),
+			IdempotentHint:  true, // Building the same source code multiple times produces the same container image.
+		},
 		InputSchema: map[string]any{
 			"type": "object",
 			"properties": map[string]any{

pkg/mcp/tools_config.go

@@ -32,6 +32,12 @@ func (t configVolumesTool) desc() *mcp.Tool {
 	return &mcp.Tool{
 		Name:        "config_volumes",
 		Description: "Manages volume configurations for a function. Can add, remove, or list volumes in func.yaml.",
+		Annotations: &mcp.ToolAnnotations{
+			Title:           "Config Volumes",
+			ReadOnlyHint:    false,
+			DestructiveHint: ptr(true),
+			IdempotentHint:  false, // Adding the same volume twice or removing a non-existent volume will fail.
+		},
 		InputSchema: map[string]any{
 			"type": "object",
 			"properties": map[string]any{
@@ -141,6 +147,12 @@ func (t configLabelsTool) desc() *mcp.Tool {
 	return &mcp.Tool{
 		Name:        "config_labels",
 		Description: "Manages label configurations for a function. Can add, remove, or list labels in func.yaml.",
+		Annotations: &mcp.ToolAnnotations{
+			Title:           "Config Labels",
+			ReadOnlyHint:    false,
+			DestructiveHint: ptr(true),
+			IdempotentHint:  false, // Adding the same label twice or removing a non-existent label will fail.
+		},
 		InputSchema: map[string]any{
 			"type": "object",
 			"properties": map[string]any{
@@ -229,6 +241,12 @@ func (t configEnvsTool) desc() *mcp.Tool {
 	return &mcp.Tool{
 		Name:        "config_envs",
 		Description: "Manages environment variable configurations for a function. Can add, remove, or list environment variables in func.yaml.",
+		Annotations: &mcp.ToolAnnotations{
+			Title:           "Config Environment Variables",
+			ReadOnlyHint:    false,
+			DestructiveHint: ptr(true),
+			IdempotentHint:  false, // Adding the same environment variable twice or removing a non-existent one will fail.
+		},
 		InputSchema: map[string]any{
 			"type": "object",
 			"properties": map[string]any{

pkg/mcp/tools_create.go

@@ -34,6 +34,12 @@ func (t createTool) desc() *mcp.Tool {
 		Name:        "create",
 		Title:       "Create Function",
 		Description: "Initialize a new Function project in the current directory (like 'git init'). Function name defaults to directory name.",
+		Annotations: &mcp.ToolAnnotations{
+			Title:           "Create Function",
+			ReadOnlyHint:    false,
+			DestructiveHint: ptr(false),
+			IdempotentHint:  false, // Running create twice on the same path fails because function files already exist.
+		},
 		InputSchema: map[string]any{
 			"type": "object",
 			"properties": map[string]any{

pkg/mcp/tools_delete.go

@@ -32,6 +32,12 @@ func (t deleteTool) desc() *mcp.Tool {
 		Name:        "delete",
 		Title:       "Delete Function",
 		Description: "Delete a deployed Function from the Kubernetes cluster.",
+		Annotations: &mcp.ToolAnnotations{
+			Title:           "Delete Function",
+			ReadOnlyHint:    false,
+			DestructiveHint: ptr(true),
+			IdempotentHint:  true, // Deleting the same function multiple times results in the same end state (function doesn't exist).
+		},
 		InputSchema: map[string]any{
 			"type": "object",
 			"properties": map[string]any{

pkg/mcp/tools_deploy.go

@@ -47,6 +47,12 @@ func (t deployTool) desc() *mcp.Tool {
 		Name:        "deploy",
 		Title:       "Deploy Function",
 		Description: "Deploy the Function to Kubernetes from the current directory. Builds the container image if needed.",
+		Annotations: &mcp.ToolAnnotations{
+			Title:           "Deploy Function",
+			ReadOnlyHint:    false,
+			DestructiveHint: ptr(false),
+			IdempotentHint:  true, // Deploying the same function configuration multiple times converges to the same desired state.
+		},
 		InputSchema: map[string]any{
 			"type": "object",
 			"properties": map[string]any{

pkg/mcp/tools_list.go

@@ -28,6 +28,11 @@ func (t listTool) desc() *mcp.Tool {
 	return &mcp.Tool{
 		Name:        "list",
 		Description: "Lists all deployed functions in the current namespace, specified namespace, or all namespaces.",
+		Annotations: &mcp.ToolAnnotations{
+			Title:          "List Functions",
+			ReadOnlyHint:   true,
+			IdempotentHint: true, // Listing functions with the same parameters multiple times returns consistent results at any point in time.
+		},
 		InputSchema: map[string]any{
 			"type": "object",
 			"properties": map[string]any{