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| 1 | +# MCP: Exposing Your API to AI Agents |
| 2 | + |
| 3 | +API Platform integrates with the [Model Context Protocol (MCP)](https://modelcontextprotocol.io/) to expose your API resources as tools and resources that AI agents (LLMs) can discover and interact with. |
| 4 | + |
| 5 | +MCP defines a standard way for AI models to discover available tools, understand their input/output schemas, and invoke them. API Platform leverages its existing metadata system to automatically generate MCP tool definitions from your resource classes. |
| 6 | + |
| 7 | +## Installation |
| 8 | + |
| 9 | +The MCP component requires the `mcp/sdk` PHP package: |
| 10 | + |
| 11 | +```console |
| 12 | +composer require mcp/sdk |
| 13 | +``` |
| 14 | + |
| 15 | +On Symfony, you also need the [MCP Bundle](https://github.com/symfony-tools/mcp-bundle): |
| 16 | + |
| 17 | +```console |
| 18 | +composer require symfony/mcp-bundle |
| 19 | +``` |
| 20 | + |
| 21 | +## Configuring the MCP Server |
| 22 | + |
| 23 | +### Symfony |
| 24 | + |
| 25 | +Enable the MCP server and configure the transport in your `config/packages/api_platform.yaml`: |
| 26 | + |
| 27 | +```yaml |
| 28 | +# config/packages/api_platform.yaml |
| 29 | +api_platform: |
| 30 | + # ... |
| 31 | + |
| 32 | +mcp: |
| 33 | + client_transports: |
| 34 | + http: true |
| 35 | + stdio: false |
| 36 | + http: |
| 37 | + path: '/mcp' |
| 38 | + session: |
| 39 | + store: 'file' |
| 40 | + directory: '%kernel.cache_dir%/mcp' |
| 41 | + ttl: 3600 |
| 42 | +``` |
| 43 | +
|
| 44 | +### Laravel |
| 45 | +
|
| 46 | +MCP is enabled by default in the Laravel configuration: |
| 47 | +
|
| 48 | +```php |
| 49 | +// config/api-platform.php |
| 50 | +return [ |
| 51 | + // ... |
| 52 | + 'mcp' => [ |
| 53 | + 'enabled' => true, |
| 54 | + ], |
| 55 | +]; |
| 56 | +``` |
| 57 | + |
| 58 | +The MCP endpoint is automatically registered at `/mcp`. |
| 59 | + |
| 60 | +## Declaring MCP Tools |
| 61 | + |
| 62 | +MCP tools let AI agents call operations on your API. Use the `McpTool` attribute inside the `mcp` option of `ApiResource`. Each tool gets a name (the array key), and its input schema is automatically derived from the class properties. |
| 63 | + |
| 64 | +### Using `mcp` on an ApiResource |
| 65 | + |
| 66 | +```php |
| 67 | +<?php |
| 68 | +// api/src/ApiResource/Book.php with Symfony or app/ApiResource/Book.php with Laravel |
| 69 | +namespace App\ApiResource; |
| 70 | + |
| 71 | +use ApiPlatform\Metadata\ApiResource; |
| 72 | +use ApiPlatform\Metadata\McpTool; |
| 73 | + |
| 74 | +#[ApiResource( |
| 75 | + operations: [], |
| 76 | + mcp: [ |
| 77 | + 'get_book_info' => new McpTool( |
| 78 | + provider: [self::class, 'provide'] |
| 79 | + ), |
| 80 | + 'update_book_status' => new McpTool( |
| 81 | + processor: [self::class, 'process'] |
| 82 | + ), |
| 83 | + ] |
| 84 | +)] |
| 85 | +class Book |
| 86 | +{ |
| 87 | + public function __construct( |
| 88 | + private ?string $title = null, |
| 89 | + private ?string $isbn = null, |
| 90 | + private ?string $status = null, |
| 91 | + ) {} |
| 92 | + |
| 93 | + // getters and setters... |
| 94 | + |
| 95 | + public static function provide(): self |
| 96 | + { |
| 97 | + return new self(title: 'API Platform Guide', isbn: '978-1234567890', status: 'available'); |
| 98 | + } |
| 99 | + |
| 100 | + public static function process($data): mixed |
| 101 | + { |
| 102 | + $data->setStatus('updated'); |
| 103 | + |
| 104 | + return $data; |
| 105 | + } |
| 106 | +} |
| 107 | +``` |
| 108 | + |
| 109 | +This declares two MCP tools: `get_book_info` (read via a [state provider](state-providers.md)) and `update_book_status` (write via a [state processor](state-processors.md)). The input schema for each tool is generated from the class properties. |
| 110 | + |
| 111 | +Note that `operations: []` means no HTTP operations are exposed — you can combine MCP tools with regular REST/GraphQL operations on the same resource if needed. |
| 112 | + |
| 113 | +### Using `McpTool` Directly as a Class Attribute |
| 114 | + |
| 115 | +For standalone tools that don't need REST operations, you can use `McpTool` as a class-level attribute: |
| 116 | + |
| 117 | +```php |
| 118 | +<?php |
| 119 | +namespace App\ApiResource; |
| 120 | + |
| 121 | +use ApiPlatform\Metadata\McpTool; |
| 122 | + |
| 123 | +#[McpTool( |
| 124 | + name: 'process_message', |
| 125 | + description: 'Process a message with priority', |
| 126 | + processor: [self::class, 'process'] |
| 127 | +)] |
| 128 | +class ProcessMessage |
| 129 | +{ |
| 130 | + public function __construct( |
| 131 | + private string $message, |
| 132 | + private int $priority = 1, |
| 133 | + ) {} |
| 134 | + |
| 135 | + // getters and setters... |
| 136 | + |
| 137 | + public static function process($data): mixed |
| 138 | + { |
| 139 | + $data->setMessage('Processed: ' . $data->getMessage()); |
| 140 | + |
| 141 | + return $data; |
| 142 | + } |
| 143 | +} |
| 144 | +``` |
| 145 | + |
| 146 | +### Returning Custom Results |
| 147 | + |
| 148 | +By default, tool results are serialized using API Platform's [serialization](serialization.md) system with structured content (JSON). If you need full control over the response, return a `CallToolResult` directly from your processor: |
| 149 | + |
| 150 | +```php |
| 151 | +<?php |
| 152 | +namespace App\ApiResource; |
| 153 | + |
| 154 | +use ApiPlatform\Metadata\ApiResource; |
| 155 | +use ApiPlatform\Metadata\McpTool; |
| 156 | +use Mcp\Schema\Content\TextContent; |
| 157 | +use Mcp\Schema\Result\CallToolResult; |
| 158 | + |
| 159 | +#[ApiResource( |
| 160 | + operations: [], |
| 161 | + mcp: [ |
| 162 | + 'generate_report' => new McpTool( |
| 163 | + description: 'Generate a markdown report', |
| 164 | + processor: [self::class, 'process'], |
| 165 | + structuredContent: false |
| 166 | + ), |
| 167 | + ] |
| 168 | +)] |
| 169 | +class Report |
| 170 | +{ |
| 171 | + public function __construct( |
| 172 | + private string $title, |
| 173 | + private string $content, |
| 174 | + ) {} |
| 175 | + |
| 176 | + // getters and setters... |
| 177 | + |
| 178 | + public static function process($data): CallToolResult |
| 179 | + { |
| 180 | + $markdown = "# {$data->getTitle()}\n\n{$data->getContent()}"; |
| 181 | + |
| 182 | + return new CallToolResult( |
| 183 | + [new TextContent($markdown)], |
| 184 | + false |
| 185 | + ); |
| 186 | + } |
| 187 | +} |
| 188 | +``` |
| 189 | + |
| 190 | +Setting `structuredContent: false` disables the automatic JSON serialization. When returning a `CallToolResult`, the response is sent as-is to the AI agent. |
| 191 | + |
| 192 | +## Declaring MCP Resources |
| 193 | + |
| 194 | +MCP resources expose read-only content that AI agents can retrieve — documentation, configuration files, reference data, etc. Use the `McpResource` attribute: |
| 195 | + |
| 196 | +```php |
| 197 | +<?php |
| 198 | +namespace App\ApiResource; |
| 199 | + |
| 200 | +use ApiPlatform\Metadata\ApiResource; |
| 201 | +use ApiPlatform\Metadata\McpResource; |
| 202 | + |
| 203 | +#[ApiResource( |
| 204 | + operations: [], |
| 205 | + mcp: [ |
| 206 | + 'api_docs' => new McpResource( |
| 207 | + uri: 'resource://my-app/documentation', |
| 208 | + name: 'App-Documentation', |
| 209 | + description: 'Application API documentation', |
| 210 | + mimeType: 'text/markdown', |
| 211 | + provider: [self::class, 'provide'] |
| 212 | + ), |
| 213 | + ] |
| 214 | +)] |
| 215 | +class Documentation |
| 216 | +{ |
| 217 | + public function __construct( |
| 218 | + private string $content, |
| 219 | + private string $uri, |
| 220 | + ) {} |
| 221 | + |
| 222 | + // getters and setters... |
| 223 | + |
| 224 | + public static function provide(): self |
| 225 | + { |
| 226 | + return new self( |
| 227 | + content: '# My API Documentation\n\nWelcome to the API.', |
| 228 | + uri: 'resource://my-app/documentation' |
| 229 | + ); |
| 230 | + } |
| 231 | +} |
| 232 | +``` |
| 233 | + |
| 234 | +The `uri` must be unique across the MCP server and follows the `resource://` URI scheme. |
| 235 | + |
| 236 | +## Structured Content |
| 237 | + |
| 238 | +By default, MCP tools return structured content: the result is serialized to JSON using API Platform's normalizers and included alongside the text representation. This gives AI agents both a human-readable and a machine-parseable version of the response. |
| 239 | + |
| 240 | +You can disable this per-tool with `structuredContent: false`, which is useful when the tool produces plain text or markdown that doesn't benefit from JSON serialization. |
| 241 | + |
| 242 | +## Validation |
| 243 | + |
| 244 | +MCP tool inputs support validation, using the same mechanisms as regular API Platform operations. |
| 245 | + |
| 246 | +On Symfony, use [Symfony Validator constraints](../symfony/validation.md): |
| 247 | + |
| 248 | +```php |
| 249 | +use Symfony\Component\Validator\Constraints as Assert; |
| 250 | + |
| 251 | +class ContactForm |
| 252 | +{ |
| 253 | + #[Assert\NotBlank] |
| 254 | + #[Assert\Length(min: 3, max: 50)] |
| 255 | + private ?string $name = null; |
| 256 | + |
| 257 | + #[Assert\NotNull] |
| 258 | + #[Assert\Email] |
| 259 | + private ?string $email = null; |
| 260 | +} |
| 261 | +``` |
| 262 | + |
| 263 | +On Laravel, use [validation rules](../laravel/validation.md): |
| 264 | + |
| 265 | +```php |
| 266 | +#[ApiResource( |
| 267 | + operations: [], |
| 268 | + mcp: [ |
| 269 | + 'submit_contact' => new McpTool( |
| 270 | + processor: [self::class, 'process'], |
| 271 | + rules: [ |
| 272 | + 'name' => 'required|min:3|max:50', |
| 273 | + 'email' => 'required|email', |
| 274 | + ] |
| 275 | + ), |
| 276 | + ] |
| 277 | +)] |
| 278 | +``` |
| 279 | + |
| 280 | +## McpTool Options |
| 281 | + |
| 282 | +The `McpTool` attribute accepts all standard [operation options](operations.md) plus: |
| 283 | + |
| 284 | +| Option | Description | |
| 285 | +|---|---| |
| 286 | +| `name` | Tool name exposed to AI agents (defaults to the `mcp` array key or method name) | |
| 287 | +| `description` | Human-readable description of the tool (defaults to class DocBlock) | |
| 288 | +| `structuredContent` | Whether to include JSON structured content in responses (default: `true`) | |
| 289 | +| `annotations` | MCP tool annotations describing behavior hints | |
| 290 | +| `icons` | List of icon URLs representing the tool | |
| 291 | +| `meta` | Arbitrary metadata | |
| 292 | + |
| 293 | +## McpResource Options |
| 294 | + |
| 295 | +The `McpResource` attribute accepts all standard [operation options](operations.md) plus: |
| 296 | + |
| 297 | +| Option | Description | |
| 298 | +|---|---| |
| 299 | +| `uri` | Unique URI identifying this resource (required, uses `resource://` scheme) | |
| 300 | +| `name` | Human-readable name for the resource | |
| 301 | +| `description` | Description of the resource (defaults to class DocBlock) | |
| 302 | +| `structuredContent` | Whether to include JSON structured content (default: `true`) | |
| 303 | +| `mimeType` | MIME type of the resource content | |
| 304 | +| `size` | Size in bytes, if known | |
| 305 | +| `annotations` | MCP resource annotations | |
| 306 | +| `icons` | List of icon URLs | |
| 307 | +| `meta` | Arbitrary metadata | |
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