feat: support sampling with tools

src/Schema/ClientCapabilities.php

@@ -30,6 +30,8 @@ public function __construct(
         public readonly ?bool $elicitation = null,
         public readonly ?array $experimental = null,
         public readonly ?array $extensions = null,
+        public readonly ?bool $samplingContext = null,
+        public readonly ?bool $samplingTools = null,
     ) {
     }
 
@@ -38,7 +40,7 @@ public function __construct(
      *     roots?: array{
      *         listChanged?: bool,
      *     },
-     *     sampling?: bool,
+     *     sampling?: array{context?: mixed, tools?: mixed}|object,
      *     elicitation?: bool,
      *     experimental?: array<string, mixed>,
      *     extensions?: array<string, mixed>,
@@ -57,8 +59,17 @@ public static function fromArray(array $data): self
         }
 
         $sampling = null;
+        $samplingContext = null;
+        $samplingTools = null;
         if (isset($data['sampling'])) {
             $sampling = true;
+            if (\is_array($data['sampling'])) {
+                $samplingContext = isset($data['sampling']['context']);
+                $samplingTools = isset($data['sampling']['tools']);
+            } elseif (\is_object($data['sampling'])) {
+                $samplingContext = property_exists($data['sampling'], 'context');
+                $samplingTools = property_exists($data['sampling'], 'tools');
+            }
         }
 
         $elicitation = null;
@@ -73,6 +84,8 @@ public static function fromArray(array $data): self
             $elicitation,
             \is_array($data['experimental'] ?? null) ? $data['experimental'] : null,
             \is_array($data['extensions'] ?? null) ? $data['extensions'] : null,
+            $samplingContext,
+            $samplingTools,
         );
     }
 
@@ -95,8 +108,14 @@ public function jsonSerialize(): array|object
             }
         }
 
-        if ($this->sampling) {
+        if ($this->sampling || $this->samplingContext || $this->samplingTools) {
             $data['sampling'] = new \stdClass();
+            if ($this->samplingContext) {
+                $data['sampling']->context = new \stdClass();
+            }
+            if ($this->samplingTools) {
+                $data['sampling']->tools = new \stdClass();
+            }
         }
 
         if ($this->elicitation) {

src/Schema/Content/SamplingMessage.php

@@ -19,17 +19,41 @@
  *
  * @phpstan-type SamplingMessageData = array{
  *     role: 'user'|'assistant',
- *     content: TextContent|ImageContent|AudioContent
+ *     content: array<string, mixed>|array<array<string, mixed>>,
+ *     _meta?: array<string, mixed>
  * }
  *
  * @author Kyrian Obikwelu <koshnawaza@gmail.com>
  */
 class SamplingMessage extends Content
 {
+    /**
+     * @param TextContent|ImageContent|AudioContent|ToolUseContent|ToolResultContent|list<TextContent|ImageContent|AudioContent|ToolUseContent|ToolResultContent> $content
+     * @param ?array<string, mixed>                                                                                                                               $meta
+     */
     public function __construct(
         public readonly Role $role,
-        public readonly TextContent|ImageContent|AudioContent $content,
+        public readonly TextContent|ImageContent|AudioContent|ToolUseContent|ToolResultContent|array $content,
+        public readonly ?array $meta = null,
     ) {
+        $contents = \is_array($content) ? $content : [$content];
+        foreach ($contents as $item) {
+            if (!$item instanceof TextContent && !$item instanceof ImageContent && !$item instanceof AudioContent && !$item instanceof ToolUseContent && !$item instanceof ToolResultContent) {
+                throw new InvalidArgumentException('Sampling message content contains an unsupported content block.');
+            }
+            if (Role::User === $role && $item instanceof ToolUseContent) {
+                throw new InvalidArgumentException('ToolUseContent is only valid in assistant sampling messages.');
+            }
+            if (Role::Assistant === $role && $item instanceof ToolResultContent) {
+                throw new InvalidArgumentException('ToolResultContent is only valid in user sampling messages.');
+            }
+        }
+
+        if (array_filter($contents, static fn ($item): bool => $item instanceof ToolResultContent)
+            && array_filter($contents, static fn ($item): bool => !$item instanceof ToolResultContent)) {
+            throw new InvalidArgumentException('Tool result messages must not contain other content types.');
+        }
+
         parent::__construct('sampling');
     }
 
@@ -47,26 +71,55 @@ public static function fromArray(array $data): self
 
         $role = Role::from($data['role']);
         $contentData = $data['content'];
-        $contentType = $contentData['type'] ?? null;
+        $isSingleContent = isset($contentData['type']);
+        $contentItems = $isSingleContent ? [$contentData] : $contentData;
+        $content = [];
 
-        $contentInstance = match ($contentType) {
-            'text' => TextContent::fromArray($contentData),
-            'image' => ImageContent::fromArray($contentData),
-            'audio' => AudioContent::fromArray($contentData),
-            default => throw new InvalidArgumentException(\sprintf('Invalid content type "%s" for SamplingMessage.', $contentType)),
-        };
+        foreach ($contentItems as $item) {
+            if (!\is_array($item)) {
+                throw new InvalidArgumentException('Invalid content block in SamplingMessage data.');
+            }
+            $content[] = self::hydrateContent($item);
+        }
 
-        return new self($role, $contentInstance);
+        return new self(
+            $role,
+            $isSingleContent ? $content[0] : $content,
+            isset($data['_meta']) && \is_array($data['_meta']) ? $data['_meta'] : null,
+        );
     }
 
     /**
      * @return SamplingMessageData
      */
     public function jsonSerialize(): array
     {
-        return [
+        $data = [
             'role' => $this->role->value,
             'content' => $this->content,
         ];
+
+        if (null !== $this->meta) {
+            $data['_meta'] = $this->meta;
+        }
+
+        return $data;
+    }
+
+    /**
+     * @param array<string, mixed> $contentData
+     */
+    private static function hydrateContent(array $contentData): TextContent|ImageContent|AudioContent|ToolUseContent|ToolResultContent
+    {
+        $contentType = $contentData['type'] ?? null;
+
+        return match ($contentType) {
+            'text' => TextContent::fromArray($contentData),
+            'image' => ImageContent::fromArray($contentData),
+            'audio' => AudioContent::fromArray($contentData),
+            'tool_use' => ToolUseContent::fromArray($contentData),
+            'tool_result' => ToolResultContent::fromArray($contentData),
+            default => throw new InvalidArgumentException(\sprintf('Invalid content type "%s" for SamplingMessage.', $contentType)),
+        };
     }
 }

src/Schema/Content/ToolResultContent.php

@@ -0,0 +1,99 @@
+<?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.
+ */
+
+namespace Mcp\Schema\Content;
+
+use Mcp\Exception\InvalidArgumentException;
+
+/**
+ * The result of a tool use, provided by the user back to the assistant.
+ */
+final class ToolResultContent extends Content
+{
+    /**
+     * @param Content[]             $content
+     * @param ?array<string, mixed> $structuredContent
+     * @param ?array<string, mixed> $meta
+     */
+    public function __construct(
+        public readonly string $toolUseId,
+        public readonly array $content,
+        public readonly ?array $structuredContent = null,
+        public readonly bool $isError = false,
+        public readonly ?array $meta = null,
+    ) {
+        foreach ($content as $item) {
+            if (!$item instanceof Content || $item instanceof self || $item instanceof ToolUseContent) {
+                throw new InvalidArgumentException('Tool result content must contain standard content blocks.');
+            }
+        }
+
+        parent::__construct('tool_result');
+    }
+
+    /**
+     * @param array<string, mixed> $data
+     */
+    public static function fromArray(array $data): self
+    {
+        if (!isset($data['toolUseId']) || !\is_string($data['toolUseId'])) {
+            throw new InvalidArgumentException('Missing or invalid "toolUseId" in ToolResultContent data.');
+        }
+        if (!isset($data['content']) || !\is_array($data['content'])) {
+            throw new InvalidArgumentException('Missing or invalid "content" in ToolResultContent data.');
+        }
+
+        $content = [];
+        foreach ($data['content'] as $item) {
+            if (!\is_array($item)) {
+                throw new InvalidArgumentException('Invalid content block in ToolResultContent data.');
+            }
+
+            $content[] = match ($item['type'] ?? null) {
+                'text' => TextContent::fromArray($item),
+                'image' => ImageContent::fromArray($item),
+                'audio' => AudioContent::fromArray($item),
+                'resource' => EmbeddedResource::fromArray($item),
+                default => throw new InvalidArgumentException(\sprintf('Unsupported tool result content type "%s".', $item['type'] ?? null)),
+            };
+        }
+
+        return new self(
+            $data['toolUseId'],
+            $content,
+            isset($data['structuredContent']) && \is_array($data['structuredContent']) ? $data['structuredContent'] : null,
+            isset($data['isError']) && true === $data['isError'],
+            isset($data['_meta']) && \is_array($data['_meta']) ? $data['_meta'] : null,
+        );
+    }
+
+    /**
+     * @return array<string, mixed>
+     */
+    public function jsonSerialize(): array
+    {
+        $data = [
+            'type' => $this->type,
+            'toolUseId' => $this->toolUseId,
+            'content' => $this->content,
+            'isError' => $this->isError,
+        ];
+
+        if (null !== $this->structuredContent) {
+            $data['structuredContent'] = $this->structuredContent;
+        }
+        if (null !== $this->meta) {
+            $data['_meta'] = $this->meta;
+        }
+
+        return $data;
+    }
+}

src/Schema/Content/ToolUseContent.php

@@ -0,0 +1,75 @@
+<?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.
+ */
+
+namespace Mcp\Schema\Content;
+
+use Mcp\Exception\InvalidArgumentException;
+
+/**
+ * A request from the assistant to call a tool.
+ */
+final class ToolUseContent extends Content
+{
+    /**
+     * @param array<string, mixed>  $input
+     * @param ?array<string, mixed> $meta
+     */
+    public function __construct(
+        public readonly string $id,
+        public readonly string $name,
+        public readonly array $input,
+        public readonly ?array $meta = null,
+    ) {
+        parent::__construct('tool_use');
+    }
+
+    /**
+     * @param array{id?: mixed, name?: mixed, input?: mixed, _meta?: mixed} $data
+     */
+    public static function fromArray(array $data): self
+    {
+        if (!isset($data['id']) || !\is_string($data['id'])) {
+            throw new InvalidArgumentException('Missing or invalid "id" in ToolUseContent data.');
+        }
+        if (!isset($data['name']) || !\is_string($data['name'])) {
+            throw new InvalidArgumentException('Missing or invalid "name" in ToolUseContent data.');
+        }
+        if (!isset($data['input']) || !\is_array($data['input'])) {
+            throw new InvalidArgumentException('Missing or invalid "input" in ToolUseContent data.');
+        }
+
+        return new self(
+            $data['id'],
+            $data['name'],
+            $data['input'],
+            isset($data['_meta']) && \is_array($data['_meta']) ? $data['_meta'] : null,
+        );
+    }
+
+    /**
+     * @return array{type: 'tool_use', id: string, name: string, input: array<string, mixed>|\stdClass, _meta?: array<string, mixed>}
+     */
+    public function jsonSerialize(): array
+    {
+        $data = [
+            'type' => $this->type,
+            'id' => $this->id,
+            'name' => $this->name,
+            'input' => $this->input ?: new \stdClass(),
+        ];
+
+        if (null !== $this->meta) {
+            $data['_meta'] = $this->meta;
+        }
+
+        return $data;
+    }
+}

src/Schema/Enum/SamplingStopReason.php

@@ -0,0 +1,20 @@
+<?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.
+ */
+
+namespace Mcp\Schema\Enum;
+
+enum SamplingStopReason: string
+{
+    case EndTurn = 'endTurn';
+    case StopSequence = 'stopSequence';
+    case MaxTokens = 'maxTokens';
+    case ToolUse = 'toolUse';
+}

src/Schema/Enum/ToolChoiceMode.php

@@ -0,0 +1,19 @@
+<?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.
+ */
+
+namespace Mcp\Schema\Enum;
+
+enum ToolChoiceMode: string
+{
+    case Auto = 'auto';
+    case Required = 'required';
+    case None = 'none';
+}