Chapter 2: Server Builder and Capability Registration

Welcome to Chapter 2: Server Builder and Capability Registration. In this part of MCP PHP SDK Tutorial: Building MCP Servers in PHP with Discovery and Transport Flexibility, you will build an intuitive mental model first, then move into concrete implementation details and practical production tradeoffs.

This chapter explains how Server::builder() composes MCP runtime behavior.

Learning Goals

• understand builder-driven server composition
• configure server info, instructions, pagination, and discovery
• register capabilities manually when discovery is not enough
• add dependency wiring (container/logger/event dispatcher) safely

Builder Responsibilities

Area	Typical Controls
Server metadata	name, version, instructions
Capability setup	discovery scan or explicit registration
Runtime dependencies	container, logger, event dispatcher
Session behavior	session store + TTL strategy

Design Guidance

• use the static builder method as the default setup path.
• keep explicit registration for business-critical handlers requiring strict ownership.
• keep capability declarations and actual handler availability aligned.

Source References

• Server Builder Guide
• PHP SDK README - Quick Start

Summary

You now have a builder-centric model for composing PHP MCP servers.

Next: Chapter 3: MCP Elements: Tools, Resources, Prompts, and Schemas

Source Code Walkthrough

examples/server/oauth-keycloak/keycloak/mcp-realm.json

The mcp-realm module in examples/server/oauth-keycloak/keycloak/mcp-realm.json handles a key part of this chapter's functionality:

{
  "realm": "mcp",
  "enabled": true,
  "registrationAllowed": false,
  "loginWithEmailAllowed": true,
  "duplicateEmailsAllowed": false,
  "resetPasswordAllowed": true,
  "editUsernameAllowed": false,
  "bruteForceProtected": true,
  "accessTokenLifespan": 300,
  "ssoSessionIdleTimeout": 1800,
  "ssoSessionMaxLifespan": 36000,
  "clients": [
    {
      "clientId": "mcp-client",
      "name": "MCP Client Application",
      "description": "Public client for MCP client applications",
      "enabled": true,
      "publicClient": true,
      "standardFlowEnabled": true,
      "directAccessGrantsEnabled": true,
      "serviceAccountsEnabled": false,
      "authorizationServicesEnabled": false,
      "fullScopeAllowed": true,
      "redirectUris": [
        "http://localhost:*",
        "http://127.0.0.1:*"
      ],
      "webOrigins": [
        "http://localhost:*",
        "http://127.0.0.1:*"
      ],
      "defaultClientScopes": [
        "openid",
        "profile",

This module is important because it defines how MCP PHP SDK Tutorial: Building MCP Servers in PHP with Discovery and Transport Flexibility implements the patterns covered in this chapter.

examples/server/oauth-microsoft/docker-compose.yml

The docker-compose module in examples/server/oauth-microsoft/docker-compose.yml handles a key part of this chapter's functionality:

services:
  php:
    build:
      context: .
      dockerfile: Dockerfile
    container_name: mcp-php-microsoft
    volumes:
      - ../../../:/app
    working_dir: /app
    env_file:
      - .env
    environment:
      AZURE_TENANT_ID: ${AZURE_TENANT_ID:-}
      AZURE_CLIENT_ID: ${AZURE_CLIENT_ID:-}
      AZURE_CLIENT_SECRET: ${AZURE_CLIENT_SECRET:-}
    command: >
      sh -c "mkdir -p /app/examples/server/oauth-microsoft/sessions;
      chmod -R 0777 /app/examples/server/oauth-microsoft/sessions;
      touch /app/examples/server/oauth-microsoft/dev.log;
      chmod 0666 /app/examples/server/oauth-microsoft/dev.log;
      touch /app/examples/server/dev.log;
      chmod 0666 /app/examples/server/dev.log;
      composer install --no-interaction --quiet 2>/dev/null || true;
      php-fpm"
    networks:
      - mcp-network

  nginx:
    image: nginx:alpine
    container_name: mcp-nginx-microsoft
    ports:
      - "${MCP_HTTP_PORT:-8000}:80"
    volumes:
      - ./nginx/default.conf:/etc/nginx/conf.d/default.conf:ro
      - ../../../:/app:ro

This module is important because it defines how MCP PHP SDK Tutorial: Building MCP Servers in PHP with Discovery and Transport Flexibility implements the patterns covered in this chapter.

composer.json

The composer module in composer.json handles a key part of this chapter's functionality:

{
  "name": "mcp/sdk",
  "description": "Model Context Protocol SDK for Client and Server applications in PHP",
  "license": "Apache-2.0",
  "type": "library",
  "authors": [
    {
      "name": "Christopher Hertel",
      "email": "mail@christopher-hertel.de"
    },
    {
      "name": "Kyrian Obikwelu",
      "email": "koshnawaza@gmail.com"
    },
    {
      "name": "Tobias Nyholm",
      "email": "tobias.nyholm@gmail.com"
    }
  ],
  "require": {
    "php": "^8.1",
    "ext-fileinfo": "*",
    "opis/json-schema": "^2.4",
    "php-http/discovery": "^1.20",
    "phpdocumentor/reflection-docblock": "^5.6 || ^6.0",
    "psr/clock": "^1.0",
    "psr/container": "^1.0 || ^2.0",
    "psr/event-dispatcher": "^1.0",
    "psr/http-client": "^1.0",
    "psr/http-factory": "^1.1",
    "psr/http-message": "^1.1 || ^2.0",
    "psr/http-server-handler": "^1.0",
    "psr/http-server-middleware": "^1.0",
    "psr/log": "^1.0 || ^2.0 || ^3.0",
    "symfony/finder": "^5.4 || ^6.4 || ^7.3 || ^8.0",

This module is important because it defines how MCP PHP SDK Tutorial: Building MCP Servers in PHP with Discovery and Transport Flexibility implements the patterns covered in this chapter.

How These Components Connect

flowchart TD
    A[mcp-realm]
    B[docker-compose]
    C[composer]
    A --> B
    B --> C