MCP Server

Built by a human using an AI assistant: 🤖 ➕ 🧠

A lot of the code in this module has been created using an AI assistant using Strikethroo & Kenkeep for improved Drupal code generation.

Overview

MCP Server lets AI assistants work with your Drupal site through the Model Context Protocol. It exposes tools, resources, resource templates, and prompts over the STDIO and HTTP transports.

This module supports both the STDIO transport, as well as the HTTP transport.

Key capabilities

No-code MCP tools

Any Tool API plugin becomes an MCP tool through configuration with MCP Server Tool Bridge.

OAuth 2.1 authorization

Per-tool scope checks with MCP Server OAuth and Simple OAuth.

Dual transport

STDIO through Drush for local clients, HTTP for remote clients.

Full protocol support

Built on the official MCP PHP SDK, MCP Server supports the full protocol.

Support for MCP resources Support for saved prompts Support for LLM sampling Support for authorization

Companion projects

Install these alongside MCP Server as needed.

Project What it adds MCP Server UI Admin pages at /admin/config/services/mcp-server: server settings, resource and resource template plugin settings, and prompt CRUD. MCP Server Tool Bridge Exposes Tool API tools as MCP tools. Manage the mappings at /admin/config/services/mcp-server/tools. MCP Server OAuth OAuth2 Bearer token authentication on /mcp and per-tool scope checks. Requires Drupal 11. MCP Server Examples Reference tool, resource template, and completion provider plugins.

composer require 'drupal/mcp_server_ui-mcp_server_ui:^1.0@beta'
composer require 'drupal/mcp_server_tool_bridge:^1.0@beta'
composer require 'drupal/mcp_server_oauth:^1.0@alpha'
composer require 'drupal/mcp_server_examples-mcp_server_examples:^1.0@beta'

MCP Server UI and MCP Server Examples use temporary Composer names. They will become drupal/mcp_server_ui and

drupal/mcp_server_examples</em> once <a href="https://git.drupalcode.org/project/project_composer/-/work_items/3583695">project_composer#3583695</a> is fixed.</div>
<h2>Requirements</h2>
<ul>
<li>Drupal 10 or 11</li>
<li>PHP 8.3 or higher</li>
<li>Drush 13 or higher, for the STDIO transport</li>
</ul>
<h2>Quick start</h2>
<pre><code class="language-bash">composer require 'drupal/mcp_server:^2.0@beta'
drush pm:enable mcp_server

Grant the Access MCP server permission to the roles that should reach the HTTP endpoint. It ships ungranted.

STDIO transport

The Drush command takes the user name or ID the session runs as. Tool calls check permissions against that account. Pass 0 for an anonymous session.

Example for Claude Desktop (~/Library/Application Support/Claude/claude_desktop_config.json):

{
  "mcpServers": {
    "drupal": {
      "command": "vendor/bin/drush",
      "args": ["mcp:server", "admin"],
      "cwd": "/path/to/your/drupal/site"
    }
  }
}

Test with the MCP Inspector:

npx @modelcontextprotocol/inspector vendor/bin/drush mcp:server admin

HTTP transport

The endpoint is https://your-drupal-site.com/mcp.

{
  "mcpServers": {
    "drupal-http": {
      "url": "https://your-drupal-site.com/mcp",
      "transport": "http"
    }
  }
}

Add it to Claude Code:

claude mcp add --transport http drupal https://your-drupal-site.com/mcp

Creating MCP tools

In code

A tool is a plugin in src/Plugin/mcp_server/Tool/ that extends ToolPluginBase and carries the #[Tool] attribute. MCP Server discovers it on cache rebuild. No configuration is needed.

namespace Drupal\my_module\Plugin\mcp_server\Tool;

use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\mcp_server\Attribute\Tool;
use Drupal\mcp_server\Plugin\ToolPluginBase;
use Mcp\Server\ClientGateway;

#[Tool(
  id: 'send_email',
  label: new TranslatableMarkup('Send Email'),
  description: new TranslatableMarkup('Sends an email to a recipient.'),
  inputSchema: [
    'type' => 'object',
    'properties' => [
      'to' => ['type' => 'string', 'description' => 'Recipient address.'],
      'subject' => ['type' => 'string'],
      'body' => ['type' => 'string'],
    ],
    'required' => ['to', 'subject', 'body'],
  ],
)]
final class SendEmail extends ToolPluginBase {

  public function execute(array $arguments, ClientGateway $gateway): mixed {
    return ['success' => TRUE];
  }

}

From Tool API, without code

1. Install MCP Server Tool Bridge and a module that provides Tool API tools, such as Tool Belt.
2. Go to /admin/config/services/mcp-server/tools and add a tool configuration.
3. Pick the Tool API tool and give it a machine name. A machine name of my_tool is listed to clients as tool_api__my_tool.
4. With MCP Server OAuth enabled, set the authentication mode and required scopes on the same form.

Authorization

Core MCP Server ships no authorization policy beyond the Access MCP server permission and the permissions of the acting user. Every tool call dispatches the SDK's Mcp\Event\RequestEvent, and companion modules subscribe to it.

MCP Server OAuth adds Bearer token authentication to /mcp. Each Tool Bridge tool gets one of two modes:

• Required: the token must carry every listed scope. Calls fail with HTTP 401 without a token and HTTP 403 with missing scopes.
• Disabled: no token check. Use this only for public, read-only tools.

It also publishes the tool scopes in the /.well-known/oauth-protected-resource metadata, so clients can discover the authorization server from the 401 response.

For API keys, mTLS, or role checks, write your own RequestEvent subscriber and throw McpAuthorizationDeniedException to deny a call.

Note: The author of MCP Server also authored and maintains Simple OAuth and Simple OAuth 2.1.

Testing with the MCP Inspector

Related projects

• Tool API: the tool plugin system the Tool Bridge exposes
• Tool Belt: ready-made Tool API tools
• Simple OAuth: the OAuth2 server MCP Server OAuth builds on

Resources

• Model Context Protocol documentation
• MCP specification
• Official MCP PHP SDK

Contributing

Report bugs and propose changes in the work items. Issues for the UI, Tool Bridge, and OAuth go in those projects' own queues.

Credits

MCP Server integrates the official MCP PHP SDK, a collaboration between the PHP Foundation and the Symfony project. The Symfony MCP Bundle inspired its architecture.