zip-ai / lib / mcp-adapter / includes / Domain / Tools / McpTool.php

McpTool.php in ZIP AI – AI Website Builder & AI Agent (Beta) 0.0.8, at lib/mcp-adapter/includes/Domain/Tools/McpTool.php

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1	<?php
2
3	/**
4	* MCP Tool component.
5	*
6	* @package McpAdapter
7	*/
8
9	declare( strict_types=1 );
10
11	namespace WP\MCP\Domain\Tools;
12
13	use WP\MCP\Domain\Contracts\McpComponentInterface;
14	use WP\MCP\Domain\Utils\AbilityArgumentNormalizer;
15	use WP\MCP\Domain\Utils\McpValidator;
16	use WP\MCP\Infrastructure\Observability\FailureReason;
17	use WP\McpSchema\Server\Tools\DTO\Tool as ToolDto;
18	use WP\McpSchema\Server\Tools\DTO\ToolAnnotations;
19	use WP_Error;
20
21	/**
22	* Tool component providing unified execution and permission checks.
23	*
24	* This class provides multiple flexible ways to create MCP tools:
25	*
26	* 1. Array configuration:
27	* ```php
28	* $tool = McpTool::fromArray([
29	* 'name' => 'uppercase-text',
30	* 'title' => 'Uppercase Text',
31	* 'description' => 'Converts text to uppercase',
32	* 'inputSchema' => ['type' => 'object', 'properties' => [...]],
33	* 'handler' => fn($args) => ['result' => strtoupper($args['text'])],
34	* 'permission' => fn() => true,
35	* 'annotations' => ['readOnlyHint' => true],
36	* ]);
37	* ```
38	*
39	* 2. From WordPress Ability (ability-backed):
40	* ```php
41	* $tool = McpTool::fromAbility($ability);
42	* ```
43	*
44	* McpTool wraps a protocol-only ToolDto for MCP serialization. Internal
45	* adapter metadata and execution wiring live on this class and are never
46	* exposed to MCP clients. Use get_protocol_dto() for protocol responses.
47	*
48	* @since 0.5.0
49	*/
50	final class McpTool implements McpComponentInterface {
51
52
53	// =========================================================================
54	// Runtime Properties
55	// =========================================================================
56
57	/**
58	* Clean Tool DTO (protocol-only).
59	*
60	* @var \WP\McpSchema\Server\Tools\DTO\Tool
61	*/
62	private ToolDto $tool;
63
64	/**
65	* Ability used for execution/permission checks (ability-backed tools).
66	*
67	* @var \WP_Ability\|null
68	*/
69	private ?\WP_Ability $ability = null;
70
71	/**
72	* Direct execution handler (callable-backed tools).
73	*
74	* @var callable\|null
75	*/
76	private $handler = null;
77
78	/**
79	* Direct permission callback (callable-backed tools).
80	*
81	* @var callable\|null
82	*/
83	private $permission_callback = null;
84
85	/**
86	* Internal adapter metadata (never exposed to clients).
87	*
88	* @var array<string, mixed>
89	*/
90	private array $adapter_meta = array();
91
92	/**
93	* Observability context tags for logging/metrics.
94	*
95	* @var array<string, mixed>
96	*/
97	private array $observability_context = array();
98
99	// =========================================================================
100	// Constructor
101	// =========================================================================
102
103	/**
104	* Private constructor - use factory methods.
105	*
106	* @param \WP\McpSchema\Server\Tools\DTO\Tool $tool The Tool DTO.
107	*/
108	private function __construct( ToolDto $tool ) {
109	$this->tool = $tool;
110	}
111
112	// =========================================================================
113	// Factory Methods
114	// =========================================================================
115
116	/**
117	* Create a tool definition from an array configuration.
118	*
119	* @param array $config The tool configuration array.
120	*
121	* @return self\|\WP_Error
122	*/
123	public static function fromArray( array $config ) {
124	if ( empty( $config['name'] ) ) {
125	return new WP_Error( 'mcp_tool_missing_name', 'Tool configuration must include a "name" field.' );
126	}
127
128	if ( ! isset( $config['handler'] ) \|\| ! is_callable( $config['handler'] ) ) {
129	return new WP_Error( 'mcp_tool_missing_handler', 'Tool configuration must include a callable "handler" field.' );
130	}
131
132	// Prepare input schema - ensure it's an object type for MCP compliance.
133	$input_schema = $config['inputSchema'] ?? array( 'type' => 'object' );
134	if ( ! isset( $input_schema['type'] ) ) {
135	$input_schema['type'] = 'object';
136	}
137
138	// Build tool data array.
139	$tool_data = array(
140	'name' => $config['name'],
141	'inputSchema' => $input_schema,
142	);
143
144	// Optional fields.
145	if ( isset( $config['title'] ) ) {
146	$tool_data['title'] = $config['title'];
147	}
148
149	if ( isset( $config['description'] ) ) {
150	$tool_data['description'] = $config['description'];
151	}
152
153	if ( isset( $config['outputSchema'] ) && is_array( $config['outputSchema'] ) ) {
154	$tool_data['outputSchema'] = $config['outputSchema'];
155	}
156
157	// Validate and prepare icons if set.
158	if ( isset( $config['icons'] ) && is_array( $config['icons'] ) && ! empty( $config['icons'] ) ) {
159	$icons_result = McpValidator::validate_icons_array( $config['icons'] );
160	if ( ! empty( $icons_result['valid'] ) ) {
161	$tool_data['icons'] = $icons_result['valid'];
162	}
163	}
164
165	// Preserve user-provided _meta as-is.
166	if ( isset( $config['meta'] ) && is_array( $config['meta'] ) && ! empty( $config['meta'] ) ) {
167	$tool_data['_meta'] = $config['meta'];
168	}
169
170	// Create the Tool DTO - wrap in try-catch since ToolAnnotations::fromArray() and ToolDto::fromArray() can throw.
171	try {
172	// Process annotations inside try-catch since ToolAnnotations::fromArray() can throw.
173	if ( isset( $config['annotations'] ) && is_array( $config['annotations'] ) && ! empty( $config['annotations'] ) ) {
174	$tool_data['annotations'] = ToolAnnotations::fromArray( $config['annotations'] );
175	}
176
177	$tool = ToolDto::fromArray( $tool_data );
178	} catch ( \Throwable $e ) {
179	return new WP_Error(
180	'mcp_tool_dto_creation_failed',
181	sprintf(
182	/* translators: %s: error message */
183	__( 'Failed to create Tool DTO: %s', 'mcp-adapter' ),
184	$e->getMessage()
185	),
186	array( 'exception' => $e )
187	);
188	}
189
190	// Optional deep validation if enabled.
191	$mcp_validation_enabled = apply_filters( 'mcp_adapter_validation_enabled', false );
192	if ( $mcp_validation_enabled ) {
193	$validation_result = McpToolValidator::validate_tool_dto( $tool );
194	if ( is_wp_error( $validation_result ) ) {
195	return $validation_result;
196	}
197	}
198
199	$instance = new self( $tool );
200	$instance->handler = $config['handler'];
201
202	if ( isset( $config['permission'] ) && is_callable( $config['permission'] ) ) {
203	$instance->permission_callback = $config['permission'];
204	}
205
206	$instance->observability_context = array(
207	'component_type' => 'tool',
208	'tool_name' => $config['name'],
209	'source' => 'array',
210	);
211
212	return $instance;
213	}
214
215	/**
216	* Create an ability-backed MCP tool.
217	*
218	* @param \WP_Ability $ability WordPress ability.
219	*
220	* @return self\|\WP_Error
221	*/
222	public static function fromAbility( \WP_Ability $ability ) {
223	$tool_data = RegisterAbilityAsMcpTool::build( $ability );
224	if ( $tool_data instanceof WP_Error ) {
225	return $tool_data;
226	}
227
228	$instance = new self( $tool_data['tool'] );
229	$instance->adapter_meta = $tool_data['adapter_meta'];
230	$instance->ability = $ability;
231
232	$instance->observability_context = array(
233	'component_type' => 'tool',
234	'tool_name' => $tool_data['tool']->getName(),
235	'ability_name' => $ability->get_name(),
236	'source' => 'ability',
237	);
238
239	return $instance;
240	}
241
242	// =========================================================================
243	// McpComponentInterface Implementation
244	// =========================================================================
245
246	/**
247	* Get the clean protocol DTO for MCP responses.
248	*
249	* @return \WP\McpSchema\Server\Tools\DTO\Tool
250	*/
251	public function get_protocol_dto(): ToolDto {
252	return $this->tool;
253	}
254
255	/**
256	* Execute the tool.
257	*
258	* @param mixed $arguments Tool arguments.
259	*
260	* @return mixed
261	*/
262	public function execute( $arguments ) {
263	$args = $this->unwrap_input_if_needed( $arguments );
264
265	if ( null !== $this->ability ) {
266	$args = AbilityArgumentNormalizer::normalize( $this->ability, $args );
267
268	try {
269	$result = $this->ability->execute( $args );
270	} catch ( \Throwable $throwable ) {
271	return new WP_Error(
272	'mcp_execution_failed',
273	$throwable->getMessage(),
274	array( 'error_type' => get_class( $throwable ) )
275	);
276	}
277	} elseif ( null !== $this->handler ) {
278	try {
279	$result = call_user_func( $this->handler, $args );
280	} catch ( \Throwable $throwable ) {
281	return new WP_Error(
282	'mcp_execution_failed',
283	$throwable->getMessage(),
284	array( 'error_type' => get_class( $throwable ) )
285	);
286	}
287	} else {
288	return new WP_Error( 'mcp_tool_no_handler', 'No tool execution strategy configured.' );
289	}
290
291	if ( $result instanceof WP_Error ) {
292	return $result;
293	}
294
295	$result = $this->wrap_output_if_needed( $result );
296
297	if ( ! is_array( $result ) ) {
298	$result = array( 'result' => $result );
299	}
300
301	return $result;
302	}
303
304	/**
305	* Unwrap tool input arguments when the input schema was transformed (flattened → object wrapper).
306	*
307	* @param mixed $arguments Raw tool arguments.
308	*
309	* @return mixed
310	*/
311	private function unwrap_input_if_needed( $arguments ) {
312	$is_transformed = true === ( $this->adapter_meta['input_schema_transformed'] ?? false );
313
314	if ( ! $is_transformed ) {
315	return $arguments;
316	}
317
318	$wrapper = $this->adapter_meta['input_schema_wrapper'] ?? 'input';
319	$wrapper = is_string( $wrapper ) && '' !== trim( $wrapper ) ? $wrapper : 'input';
320
321	return is_array( $arguments ) ? ( $arguments[ $wrapper ] ?? null ) : null;
322	}
323
324	/**
325	* Wrap tool results when the output schema was transformed (flattened → object wrapper).
326	*
327	* @param mixed $result Raw result.
328	*
329	* @return mixed
330	*/
331	private function wrap_output_if_needed( $result ) {
332	$is_transformed = true === ( $this->adapter_meta['output_schema_transformed'] ?? false );
333
334	if ( ! $is_transformed ) {
335	return $result;
336	}
337
338	$wrapper = $this->adapter_meta['output_schema_wrapper'] ?? 'result';
339	$wrapper = is_string( $wrapper ) && '' !== trim( $wrapper ) ? $wrapper : 'result';
340
341	return array( $wrapper => $result );
342	}
343
344	/**
345	* Check whether the current request has permission to execute this tool.
346	*
347	* @param mixed $arguments Tool arguments.
348	*
349	* @return bool\|\WP_Error
350	*/
351	public function check_permission( $arguments ) {
352	$args = $this->unwrap_input_if_needed( $arguments );
353
354	// Ability-backed tools delegate to the ability's permission system.
355	if ( null !== $this->ability ) {
356	$args = AbilityArgumentNormalizer::normalize( $this->ability, $args );
357
358	try {
359	return $this->ability->check_permissions( $args );
360	} catch ( \Throwable $throwable ) {
361	return new WP_Error(
362	'mcp_permission_check_failed',
363	$throwable->getMessage(),
364	array( 'error_type' => get_class( $throwable ) )
365	);
366	}
367	}
368
369	// Callable-backed tools use their required permission callback.
370	if ( null !== $this->permission_callback ) {
371	try {
372	$result = call_user_func( $this->permission_callback, $args );
373
374	return $result instanceof WP_Error ? $result : (bool) $result;
375	} catch ( \Throwable $throwable ) {
376	return new WP_Error(
377	'mcp_permission_check_failed',
378	$throwable->getMessage(),
379	array( 'error_type' => get_class( $throwable ) )
380	);
381	}
382	}
383
384	// Defensive fallback: should never reach here if factories are used correctly.
385	return new WP_Error(
386	'mcp_permission_denied',
387	'Access denied.',
388	array(
389	'failure_reason' => FailureReason::NO_PERMISSION_STRATEGY,
390	'tool_name' => $this->tool->getName(),
391	)
392	);
393	}
394
395	// =========================================================================
396	// Private Helper Methods
397	// =========================================================================
398
399	/**
400	* Get internal adapter metadata for this tool.
401	*
402	* @return array<string, mixed>
403	*/
404	public function get_adapter_meta(): array {
405	return $this->adapter_meta;
406	}
407
408	/**
409	* Get observability context tags for logging/metrics.
410	*
411	* @return array<string, mixed>
412	*/
413	public function get_observability_context(): array {
414	return $this->observability_context;
415	}
416	}
417