[Schema][Server] Harden sampling tools against the spec (#420)

* harden sampling tools against the spec Report tool-flow violations as -32602 instead of dropping the request, accept resource_link in tool results, gate tools on sampling.tools, and reject empty content. * normalize keyed content arrays to lists array_filter() and friends preserve keys, and a keyed array serializes as a JSON object instead of the content-block array the schema requires.
2026-08-15 04:13:53 +02:00 · 2026-08-15 04:13:53 +02:00 · 43815e38a8
commit 43815e38a8
parent becce29c41
1 changed files with 1212 additions and 167 deletions
--- a/tests/Integration/Fixture/sampling_tools.php
+++ b/tests/Integration/Fixture/sampling_tools.php
@ -0,0 +1,78 @@
+<?php
+
+/*
+ * This file is part of the official PHP MCP SDK.
+ *
+ * A collaboration between Symfony and the PHP Foundation.
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+/*
+ * Server for {@see \Mcp\Tests\Integration\SamplingToolsTest}.
+ */
+
+use Mcp\Schema\Content\SamplingMessage;
+use Mcp\Schema\Content\TextContent;
+use Mcp\Schema\Content\ToolResultContent;
+use Mcp\Schema\Content\ToolUseContent;
+use Mcp\Schema\Enum\Role;
+use Mcp\Schema\Tool;
+use Mcp\Server;
+use Mcp\Server\RequestContext;
+use Mcp\Server\Transport\StdioTransport;
+
+require_once dirname(__DIR__, 3).'/vendor/autoload.php';
+
+$weather = new Tool(
+    'get_weather',
+    null,
+    ['type' => 'object', 'properties' => ['city' => ['type' => 'string']], 'required' => ['city']],
+    'Get current weather for a city',
+    null,
+);
+
+Server::builder()
+    ->setServerInfo('integration-server', '1.0.0')
+    ->addTool(
+        static function (RequestContext $context, string $city) use ($weather): string {
+            $gateway = $context->getClientGateway();
+
+            // The spec forbids sending tools to a client that did not advertise
+            // sampling.tools, so the loop is only entered when it did.
+            if (!$gateway->supportsSamplingTools()) {
+                return 'client cannot use tools during sampling';
+            }
+
+            $messages = [new SamplingMessage(Role::User, new TextContent(sprintf('Weather in %s?', $city)))];
+
+            $answer = $gateway->sample($messages, maxTokens: 64, options: ['tools' => [$weather]]);
+            $messages[] = new SamplingMessage(Role::Assistant, $answer->content);
+
+            $toolResults = [];
+            foreach ($answer->getContentBlocks() as $block) {
+                if ($block instanceof ToolUseContent) {
+                    $toolResults[] = new ToolResultContent(
+                        $block->id,
+                        [new TextContent(sprintf('%s: 18 C', $block->input['city'] ?? 'unknown'))],
+                    );
+                }
+            }
+
+            if ([] === $toolResults) {
+                return 'the model asked for no tools';
+            }
+
+            $messages[] = new SamplingMessage(Role::User, $toolResults);
+
+            $final = $gateway->sample($messages, maxTokens: 64, options: ['tools' => [$weather]]);
+            assert($final->content instanceof TextContent);
+
+            return sprintf('%s (%s)', $final->content->text, $final->stopReason);
+        },
+        name: 'weather_report',
+        description: 'Reports weather by running a sampling tool loop.',
+    )
+    ->build()
+    ->run(new StdioTransport());