MCP client server

This example is a renderer plugin that registers a remote MCP client server so Harbor's chat agent can discover and call tools from an external MCP endpoint over Streamable HTTP or legacy SSE.

Use hc.mcp.registerServer when your plugin integrates a hosted MCP service (for example WordPress, a team API gateway, or a SaaS MCP bridge). Registrations are activation-scoped: Harbor connects while the plugin is enabled and removes the server when you dispose the returned handle or the plugin unloads. Plugin-owned servers appear as read-only rows in Settings → AI & MCP with plugin attribution; they are not copied into user MCP settings.

See hc.mcp for the full API reference and Permissions for the mcp capability flag.

manifest.json

{
  "id": "com.example.wordpress-mcp",
  "name": "WordPress MCP",
  "version": "1.0.0",
  "summary": "Connect Harbor's chat agent to WordPress MCP tools.",
  "engines": { "harborclient": ">=2.3.0" },
  "renderer": "dist/renderer.js",
  "permissions": ["mcp"]
}

MCP client registration is runtime-only — no contributes entry is required. Declare the mcp permission so HarborClient shows it in the install confirmation dialog.

src/renderer.tsx

import type { PluginContext } from '@harborclient/sdk';

/**
 * Registers the WordPress MCP client server when the plugin activates.
 */
export function activate(hc: PluginContext): void {
  hc.mcp.registerServer({
    name: 'WordPress',
    icon: 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8z8BQDwAEhQGAhKmMIQAAAABJRU5ErkJggg==',
    serverURL: 'https://public-api.wordpress.com/wpcom/v2/mcp/v1',
    enabled: true,
    headers: [{ key: 'Authorization', value: 'Bearer YOUR_TOKEN' }]
  });
}

Registration disposables are tracked automatically — HarborClient tears down the registration when the plugin deactivates.

Settings appearance

After activation, Settings → AI & MCP → MCP Client lists the server with:

• The display name and optional icon data URI you provided
• Connection status and discovered tool count
• A Provided by <plugin name> attribution line
• No Edit or Delete actions (plugin-owned rows are read-only)

Users can still add their own MCP client servers manually in the same settings section.

Tool naming

Discovered tools are prefixed with mcp__ in the chat agent tool list, using the same naming scheme as user-configured MCP client servers. Harbor routes tool calls back to the matching remote server automatically.

Lifecycle notes

• Register during activate(hc) — call hc.mcp.registerServer once the plugin is ready to expose the endpoint.
• Dispose on deactivation — registration disposables are tracked automatically; dispose custom resources in deactivate() if needed.
• Do not persist in user MCP settings — if you need durable configuration, store tokens or URLs in hc.storage and pass them into headers or serverURL at registration time.
• Icon constraint — optional icon must be a data:image/png;base64,... or data:image/svg+xml;base64,... URI for safe display in settings.