feat: add external MCP server target support and unassigned targets

Author: aidandaly24

src/cli/commands/add/actions.ts

@@ -66,6 +66,9 @@ export interface ValidatedAddGatewayOptions {
 export interface ValidatedAddGatewayTargetOptions {
   name: string;
   description?: string;
+  type?: string;
+  source?: 'existing-endpoint' | 'create-new';
+  endpoint?: string;
   language: 'Python' | 'TypeScript' | 'Other';
   exposure: 'mcp-runtime' | 'behind-gateway';
   agents?: string;
@@ -304,6 +307,8 @@ function buildGatewayTargetConfig(options: ValidatedAddGatewayTargetOptions): Ad
     sourcePath,
     language: options.language,
     exposure: options.exposure,
+    source: options.source,
+    endpoint: options.endpoint,
     host: options.exposure === 'mcp-runtime' ? 'AgentCoreRuntime' : options.host!,
     toolDefinition: {
       name: options.name,

src/cli/commands/add/command.tsx

@@ -262,6 +262,9 @@ export function registerAdd(program: Command) {
     .description('Add a gateway target to the project')
     .option('--name <name>', 'Tool name')
     .option('--description <desc>', 'Tool description')
+    .option('--type <type>', 'Target type: mcpServer or lambda')
+    .option('--source <source>', 'Source: existing-endpoint or create-new')
+    .option('--endpoint <url>', 'MCP server endpoint URL')
     .option('--language <lang>', 'Language: Python or TypeScript')
     .option('--exposure <mode>', 'Exposure mode: mcp-runtime or behind-gateway')
     .option('--agents <names>', 'Comma-separated agent names (for mcp-runtime)')

src/cli/commands/add/types.ts

@@ -45,6 +45,9 @@ export interface AddGatewayResult {
 export interface AddGatewayTargetOptions {
   name?: string;
   description?: string;
+  type?: string;
+  source?: string;
+  endpoint?: string;
   language?: 'Python' | 'TypeScript' | 'Other';
   exposure?: 'mcp-runtime' | 'behind-gateway';
   agents?: string;

src/cli/commands/add/validate.ts

@@ -189,6 +189,31 @@ export async function validateAddGatewayTargetOptions(options: AddGatewayTargetO
     return { valid: false, error: '--name is required' };
   }
 
+  if (options.type && options.type !== 'mcpServer' && options.type !== 'lambda') {
+    return { valid: false, error: 'Invalid type. Valid options: mcpServer, lambda' };
+  }
+
+  if (options.source && options.source !== 'existing-endpoint' && options.source !== 'create-new') {
+    return { valid: false, error: 'Invalid source. Valid options: existing-endpoint, create-new' };
+  }
+
+  if (options.source === 'existing-endpoint') {
+    if (!options.endpoint) {
+      return { valid: false, error: '--endpoint is required when source is existing-endpoint' };
+    }
+
+    try {
+      const url = new URL(options.endpoint);
+      if (url.protocol !== 'http:' && url.protocol !== 'https:') {
+        return { valid: false, error: 'Endpoint must use http:// or https:// protocol' };
+      }
+    } catch {
+      return { valid: false, error: 'Endpoint must be a valid URL (e.g. https://example.com/mcp)' };
+    }
+
+    return { valid: true };
+  }
+
   if (!options.language) {
     return { valid: false, error: '--language is required' };
   }

src/cli/operations/mcp/create-mcp.ts

@@ -198,6 +198,57 @@ async function validateCredentialName(credentialName: string): Promise<void> {
   }
 }
 
+/**
+ * Create an external MCP server target (existing endpoint).
+ */
+export async function createExternalGatewayTarget(config: AddGatewayTargetConfig): Promise<CreateToolResult> {
+  if (!config.endpoint) {
+    throw new Error('Endpoint URL is required for external MCP server targets.');
+  }
+
+  const configIO = new ConfigIO();
+  const mcpSpec: AgentCoreMcpSpec = configIO.configExists('mcp')
+    ? await configIO.readMcpSpec()
+    : { agentCoreGateways: [], unassignedTargets: [] };
+
+  const target: AgentCoreGatewayTarget = {
+    name: config.name,
+    targetType: 'mcpServer',
+    endpoint: config.endpoint,
+    toolDefinitions: [config.toolDefinition],
+    ...(config.outboundAuth && { outboundAuth: config.outboundAuth }),
+  };
+
+  if (config.gateway && config.gateway !== 'skip-for-now') {
+    // Assign to specific gateway
+    const gateway = mcpSpec.agentCoreGateways.find(g => g.name === config.gateway);
+    if (!gateway) {
+      throw new Error(`Gateway "${config.gateway}" not found.`);
+    }
+
+    // Check for duplicate target name
+    if (gateway.targets.some(t => t.name === config.name)) {
+      throw new Error(`Target "${config.name}" already exists in gateway "${gateway.name}".`);
+    }
+
+    gateway.targets.push(target);
+  } else {
+    // Add to unassigned targets
+    mcpSpec.unassignedTargets ??= [];
+
+    // Check for duplicate target name in unassigned targets
+    if (mcpSpec.unassignedTargets.some((t: AgentCoreGatewayTarget) => t.name === config.name)) {
+      throw new Error(`Unassigned target "${config.name}" already exists.`);
+    }
+
+    mcpSpec.unassignedTargets.push(target);
+  }
+
+  await configIO.writeMcpSpec(mcpSpec);
+
+  return { mcpDefsPath: '', toolName: config.name, projectPath: '' };
+}
+
 /**
  * Create an MCP tool (MCP runtime or behind gateway).
  */

src/cli/tui/screens/mcp/AddGatewayTargetFlow.tsx

@@ -1,3 +1,4 @@
+import { createExternalGatewayTarget } from '../../../operations/mcp/create-mcp';
 import { ErrorPrompt, Panel, Screen, TextInput, WizardSelect } from '../../components';
 import type { SelectableItem } from '../../components';
 import { HELP_TEXT } from '../../constants';
@@ -114,14 +115,25 @@ export function AddGatewayTargetFlow({
         loading: true,
         loadingMessage: 'Creating MCP tool...',
       });
-      void createTool(config).then(result => {
-        if (result.ok) {
-          const { toolName, projectPath } = result.result;
-          setFlow({ name: 'create-success', toolName, projectPath });
-          return;
-        }
-        setFlow({ name: 'error', message: result.error });
-      });
+
+      if (config.source === 'existing-endpoint') {
+        void createExternalGatewayTarget(config)
+          .then((result: { toolName: string; projectPath: string }) => {
+            setFlow({ name: 'create-success', toolName: result.toolName, projectPath: result.projectPath });
+          })
+          .catch((err: Error) => {
+            setFlow({ name: 'error', message: err instanceof Error ? err.message : 'Unknown error' });
+          });
+      } else {
+        void createTool(config).then(result => {
+          if (result.ok) {
+            const { toolName, projectPath } = result.result;
+            setFlow({ name: 'create-success', toolName, projectPath });
+            return;
+          }
+          setFlow({ name: 'error', message: result.error });
+        });
+      }
     },
     [createTool]
   );

src/cli/tui/screens/mcp/AddGatewayTargetScreen.tsx

@@ -13,7 +13,13 @@ import { HELP_TEXT } from '../../constants';
 import { useListNavigation, useMultiSelectNavigation } from '../../hooks';
 import { generateUniqueName } from '../../utils';
 import type { AddGatewayTargetConfig, ComputeHost, ExposureMode, TargetLanguage } from './types';
-import { COMPUTE_HOST_OPTIONS, EXPOSURE_MODE_OPTIONS, MCP_TOOL_STEP_LABELS, TARGET_LANGUAGE_OPTIONS } from './types';
+import {
+  COMPUTE_HOST_OPTIONS,
+  EXPOSURE_MODE_OPTIONS,
+  MCP_TOOL_STEP_LABELS,
+  SOURCE_OPTIONS,
+  TARGET_LANGUAGE_OPTIONS,
+} from './types';
 import { useAddGatewayTargetWizard } from './useAddGatewayTargetWizard';
 import { Box, Text } from 'ink';
 import React, { useMemo } from 'react';
@@ -35,6 +41,11 @@ export function AddGatewayTargetScreen({
 }: AddGatewayTargetScreenProps) {
   const wizard = useAddGatewayTargetWizard(existingGateways, existingAgents);
 
+  const sourceItems: SelectableItem[] = useMemo(
+    () => SOURCE_OPTIONS.map(o => ({ id: o.id, title: o.title, description: o.description })),
+    []
+  );
+
   const languageItems: SelectableItem[] = useMemo(
     () => TARGET_LANGUAGE_OPTIONS.map(o => ({ id: o.id, title: o.title, description: o.description })),
     []
@@ -52,7 +63,10 @@ export function AddGatewayTargetScreen({
   );
 
   const gatewayItems: SelectableItem[] = useMemo(
-    () => existingGateways.map(g => ({ id: g, title: g })),
+    () => [
+      ...existingGateways.map(g => ({ id: g, title: g })),
+      { id: 'skip-for-now', title: 'Skip for now', description: 'Create unassigned target' },
+    ],
     [existingGateways]
   );
 
@@ -63,16 +77,24 @@ export function AddGatewayTargetScreen({
 
   const agentItems: SelectableItem[] = useMemo(() => existingAgents.map(a => ({ id: a, title: a })), [existingAgents]);
 
+  const isSourceStep = wizard.step === 'source';
   const isLanguageStep = wizard.step === 'language';
   const isExposureStep = wizard.step === 'exposure';
   const isAgentsStep = wizard.step === 'agents';
   const isGatewayStep = wizard.step === 'gateway';
   const isHostStep = wizard.step === 'host';
-  const isTextStep = wizard.step === 'name';
+  const isTextStep = wizard.step === 'name' || wizard.step === 'endpoint';
   const isConfirmStep = wizard.step === 'confirm';
   const noGatewaysAvailable = isGatewayStep && existingGateways.length === 0;
   const noAgentsAvailable = isAgentsStep && existingAgents.length === 0;
 
+  const sourceNav = useListNavigation({
+    items: sourceItems,
+    onSelect: item => wizard.setSource(item.id as 'existing-endpoint' | 'create-new'),
+    onExit: () => wizard.goBack(),
+    isActive: isSourceStep,
+  });
+
   const languageNav = useListNavigation({
     items: languageItems,
     onSelect: item => wizard.setLanguage(item.id as TargetLanguage),
@@ -132,6 +154,15 @@ export function AddGatewayTargetScreen({
   return (
     <Screen title="Add MCP Tool" onExit={onExit} helpText={helpText} headerContent={headerContent}>
       <Panel>
+        {isSourceStep && (
+          <WizardSelect
+            title="Select source"
+            description="How would you like to create this MCP tool?"
+            items={sourceItems}
+            selectedIndex={sourceNav.selectedIndex}
+          />
+        )}
+
         {isLanguageStep && (
           <WizardSelect title="Select language" items={languageItems} selectedIndex={languageNav.selectedIndex} />
         )}
@@ -180,27 +211,43 @@ export function AddGatewayTargetScreen({
         {isTextStep && (
           <TextInput
             key={wizard.step}
-            prompt={MCP_TOOL_STEP_LABELS[wizard.step]}
-            initialValue={generateUniqueName('mytool', existingToolNames)}
-            onSubmit={wizard.setName}
+            prompt={wizard.step === 'endpoint' ? 'MCP server endpoint URL' : MCP_TOOL_STEP_LABELS[wizard.step]}
+            initialValue={
+              wizard.step === 'endpoint' ? 'https://example.com/mcp' : generateUniqueName('mytool', existingToolNames)
+            }
+            onSubmit={wizard.step === 'endpoint' ? wizard.setEndpoint : wizard.setName}
             onCancel={() => (wizard.currentIndex === 0 ? onExit() : wizard.goBack())}
-            schema={ToolNameSchema}
-            customValidation={value => !existingToolNames.includes(value) || 'Tool name already exists'}
+            schema={wizard.step === 'name' ? ToolNameSchema : undefined}
+            customValidation={
+              wizard.step === 'name'
+                ? value => !existingToolNames.includes(value) || 'Tool name already exists'
+                : undefined
+            }
           />
         )}
 
         {isConfirmStep && (
           <ConfirmReview
             fields={[
               { label: 'Name', value: wizard.config.name },
-              { label: 'Language', value: wizard.config.language },
-              { label: 'Exposure', value: isMcpRuntime ? 'MCP Runtime' : 'Behind Gateway' },
+              {
+                label: 'Source',
+                value: wizard.config.source === 'existing-endpoint' ? 'Existing endpoint' : 'Create new',
+              },
+              ...(wizard.config.endpoint ? [{ label: 'Endpoint', value: wizard.config.endpoint }] : []),
+              ...(wizard.config.source === 'create-new' ? [{ label: 'Language', value: wizard.config.language }] : []),
+              ...(wizard.config.source === 'create-new'
+                ? [{ label: 'Exposure', value: isMcpRuntime ? 'MCP Runtime' : 'Behind Gateway' }]
+                : []),
               ...(isMcpRuntime && wizard.config.selectedAgents.length > 0
                 ? [{ label: 'Agents', value: wizard.config.selectedAgents.join(', ') }]
                 : []),
               ...(!isMcpRuntime && wizard.config.gateway ? [{ label: 'Gateway', value: wizard.config.gateway }] : []),
-              { label: 'Host', value: wizard.config.host },
-              { label: 'Source', value: wizard.config.sourcePath },
+              ...(!isMcpRuntime && !wizard.config.gateway
+                ? [{ label: 'Gateway', value: '(none - assign later)' }]
+                : []),
+              ...(wizard.config.source === 'create-new' ? [{ label: 'Host', value: wizard.config.host }] : []),
+              ...(wizard.config.source === 'create-new' ? [{ label: 'Source', value: wizard.config.sourcePath }] : []),
             ]}
           />
         )}

src/cli/tui/screens/mcp/types.ts

@@ -47,7 +47,16 @@ export type ComputeHost = 'Lambda' | 'AgentCoreRuntime';
  * - host: Select compute host (only if behind-gateway)
  * - confirm: Review and confirm
  */
-export type AddGatewayTargetStep = 'name' | 'language' | 'exposure' | 'agents' | 'gateway' | 'host' | 'confirm';
+export type AddGatewayTargetStep =
+  | 'name'
+  | 'source'
+  | 'endpoint'
+  | 'language'
+  | 'exposure'
+  | 'agents'
+  | 'gateway'
+  | 'host'
+  | 'confirm';
 
 export type TargetLanguage = 'Python' | 'TypeScript' | 'Other';
 
@@ -57,6 +66,10 @@ export interface AddGatewayTargetConfig {
   sourcePath: string;
   language: TargetLanguage;
   exposure: ExposureMode;
+  /** Source type for external endpoints */
+  source?: 'existing-endpoint' | 'create-new';
+  /** External endpoint URL */
+  endpoint?: string;
   /** Gateway name (only when exposure = behind-gateway) */
   gateway?: string;
   /** Compute host (AgentCoreRuntime for mcp-runtime, Lambda or AgentCoreRuntime for behind-gateway) */
@@ -75,6 +88,8 @@ export interface AddGatewayTargetConfig {
 
 export const MCP_TOOL_STEP_LABELS: Record<AddGatewayTargetStep, string> = {
   name: 'Name',
+  source: 'Source',
+  endpoint: 'Endpoint',
   language: 'Language',
   exposure: 'Exposure',
   agents: 'Agents',
@@ -93,6 +108,11 @@ export const AUTHORIZER_TYPE_OPTIONS = [
   { id: 'NONE', title: 'None', description: 'No authorization required — gateway is publicly accessible' },
 ] as const;
 
+export const SOURCE_OPTIONS = [
+  { id: 'existing-endpoint', title: 'Existing endpoint', description: 'Connect to an existing MCP server' },
+  { id: 'create-new', title: 'Create new', description: 'Scaffold a new MCP server' },
+] as const;
+
 export const TARGET_LANGUAGE_OPTIONS = [
   { id: 'Python', title: 'Python', description: 'FastMCP Python server' },
   { id: 'TypeScript', title: 'TypeScript', description: 'MCP TypeScript server' },