Build an MCP Server

Prerequisites

• A Symfony application
• Symfony AI MCP Bundle

Step 1: Install the MCP Bundle

The MCP Bundle integrates the official mcp/sdk PHP package into your Symfony application:

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composer require symfony/mcp-bundle

Step 2: Configure Routing

Add the MCP route to your routing configuration. This exposes the HTTP endpoint that MCP clients connect to:

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# config/routes.yaml
mcp:
    resource: .
    type: mcp

Step 3: Create a Tool

Use the #[McpTool] attribute on a method to expose it as a callable tool. MCP clients see the tool name and can invoke it with parameters:

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namespace App\Mcp;

use Mcp\Capability\Attribute\McpTool;

class CurrentTimeTool
{
    #[McpTool(name: 'current-time')]
    public function getCurrentTime(string $format = 'Y-m-d H:i:s'): string
    {
        return (new \DateTime('now', new \DateTimeZone('UTC')))->format($format);
    }
}

Step 4: Configure Transport

Declare your server and the transports it offers. The STDIO transport is used by command-line clients; HTTP is used by web-based clients and the MCP Inspector. A server exposes only what its capability lists name, so ['*'] hands it everything you annotate:

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# config/packages/mcp.yaml
mcp:
    servers:
        default:
            name: 'my-app'
            version: '1.0.0'
            description: 'My Symfony MCP server'

            transports:
                stdio: true
                http: true

            http:
                path: /_mcp

            registry: '*'

Step 5: Create a Prompt

Prompts provide system instructions that AI clients can request. Use the #[McpPrompt] attribute and return an array of messages:

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namespace App\Mcp;

use Mcp\Capability\Attribute\McpPrompt;

class TimePrompts
{
    #[McpPrompt(name: 'time-analysis')]
    public function getTimeAnalysisPrompt(): array
    {
        return [
            ['role' => 'user', 'content' => 'You are a time management expert.'],
        ];
    }
}

Step 6: Create a Resource

Resources expose static data that AI clients can read. Use the #[McpResource] attribute with a URI and a name:

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namespace App\Mcp;

use Mcp\Capability\Attribute\McpResource;

class TimeResource
{
    #[McpResource(uri: 'time://current', name: 'current-time')]
    public function getCurrentTimeResource(): array
    {
        return [
            'uri' => 'time://current',
            'mimeType' => 'text/plain',
            'text' => (new \DateTime('now'))->format('Y-m-d H:i:s'),
        ];
    }
}

Step 7: Test with an MCP Client

To connect Claude Desktop (or any MCP-compatible client) to your server, add an entry to the client's configuration file pointing at your Symfony console command for STDIO transport:

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{
    "mcpServers": {
        "my-app": {
            "command": "php /path/to/project/bin/console mcp:server"
        }
    }
}

For the HTTP transport, point the client at your application's MCP endpoint instead:

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{
    "mcpServers": {
        "my-app": {
            "url": "http://localhost:8000/_mcp"
        }
    }
}

Learn More

• MCP Bundle - Full configuration, session storage, and event system
• Model Context Protocol Specification - The official MCP standard
• MCP PHP SDK - Documentation for the official MCP SDK for PHP