File Server/Handler/Request/CallToolRequestHandler.php

1:	<?php
2:
3:	declare(strict_types=1);
4:
5:	/**
6:	* This file is part of the Nexus MCP SDK package.
7:	*
8:	* (c) 2026 John Paul E. Balandan, CPA <paulbalandan@gmail.com>
9:	*
10:	* For the full copyright and license information, please view
11:	* the LICENSE file that was distributed with this source code.
12:	*/
13:
14:	namespace Nexus\Mcp\Server\Handler\Request;
15:
16:	use Nexus\Mcp\Core\Exception\AbstractJsonRpcProtocolException;
17:	use Nexus\Mcp\Core\Handler\AbstractContext;
18:	use Nexus\Mcp\Core\Handler\RequestHandlerInterface;
19:	use Nexus\Mcp\Core\Schema\ContentBlock\TextContent;
20:	use Nexus\Mcp\Core\Schema\JsonRpc\JsonRpcRequest;
21:	use Nexus\Mcp\Core\Schema\Request\CallToolRequest;
22:	use Nexus\Mcp\Core\Schema\Result\CallToolResult;
23:	use Nexus\Mcp\Server\Exception\ToolOutputValidationException;
24:	use Nexus\Mcp\Server\ServerContext;
25:	use Nexus\Mcp\Server\Tool\ToolStoreInterface;
26:	use Psr\Log\LoggerInterface;
27:	use Psr\Log\NullLogger;
28:
29:	/**
30:	* Handles the `tools/call` request by delegating to a `ToolStoreInterface`.
31:	*
32:	* @implements RequestHandlerInterface<'tools/call', CallToolResult, ServerContext>
33:	*/
34:	final readonly class CallToolRequestHandler implements RequestHandlerInterface
35:	{
36:	public function __construct(private ToolStoreInterface $store, private LoggerInterface $logger = new NullLogger())
37:	{
38:	}
39:
40:	#[\Override]
41:	public function handle(JsonRpcRequest $request, AbstractContext $context): CallToolResult
42:	{
43:	\assert($request instanceof CallToolRequest);
44:	\assert($context instanceof ServerContext);
45:
46:	try {
47:	$result = $this->store->call($request->params->name, $request->params->arguments, $context);
48:
49:	// Spec, "Structured Content": "For backwards compatibility, a tool that returns
50:	// structured content SHOULD also return the serialized JSON in a TextContent block."
51:	if (null !== $result->structuredContent && [] === $result->content) {
52:	return new CallToolResult(
53:	content: [new TextContent(text: json_encode(
54:	$result->structuredContent,
55:	\JSON_THROW_ON_ERROR \| \JSON_UNESCAPED_SLASHES \| \JSON_UNESCAPED_UNICODE,
56:	))],
57:	structuredContent: $result->structuredContent,
58:	isError: $result->isError,
59:	meta: $result->meta,
60:	);
61:	}
62:
63:	return $result;
64:	} catch (AbstractJsonRpcProtocolException $e) {
65:	throw $e;
66:	} catch (ToolOutputValidationException $e) {
67:	$this->logger->error(
68:	'Tool returned structuredContent that does not conform to its outputSchema.',
69:	['tool' => $request->params->name, 'exception' => $e],
70:	);
71:
72:	return new CallToolResult(
73:	content: [new TextContent(text: 'Tool execution failed.')],
74:	isError: true,
75:	);
76:	} catch (\Throwable $e) {
77:	// Generic peer-facing text. Raw $e->getMessage() can carry paths or secrets.
78:	$this->logger->error(
79:	'Uncaught tool executor exception. Returning generic error to peer.',
80:	['tool' => $request->params->name, 'exception' => $e],
81:	);
82:
83:	return new CallToolResult(
84:	content: [new TextContent(text: 'Tool execution failed.')],
85:	isError: true,
86:	);
87:	}
88:	}
89:	}
90:

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