---
title: Parallele Tool-Nutzung
url: https://platform.claude.com/docs/de/agents-and-tools/tool-use/parallel-tool-use
description: Parallele Tool-Aufrufe aktivieren, formatieren und deaktivieren, mit Hinweisen zum Nachrichtenverlauf und zur Fehlerbehebung.
---

Standardmäßig kann Claude in einer einzigen Antwort mehrere Tools aufrufen. Diese Seite behandelt, wie du diese Aufrufe ausführst, wie du den Nachrichtenverlauf formatierst, damit die Parallelität weiterhin funktioniert, und wie du die parallele „tool use“ (Tool-Nutzung) deaktivierst, wenn du das brauchst. Für den Ablauf mit einem einzelnen Aufruf siehe [Tool-Aufrufe verarbeiten](https://platform.claude.com/docs/de/agents-and-tools/tool-use/handle-tool-calls).

## Ausführungssemantik

Wenn Claude Tools aufruft, hat die Antwort einen `stop_reason` von `tool_use` und kann mehrere `tool_use`-Blöcke in einem einzigen Assistant-Turn enthalten. Wie du diese Aufrufe ausführst, ist deine Entscheidung. Die API schreibt keine Ausführungsreihenfolge vor: Du kannst die Aufrufe nebenläufig ausführen (`Promise.all`, `asyncio.gather`), sequenziell in der Reihenfolge, in der sie erscheinen, oder in jeder Kombination, die zu deinen Tools passt.

Wähle die Strategie danach, was deine Tools tun. Unabhängige, rein lesende Operationen lassen sich in der Regel sicher parallel ausführen, um die Latenz zu senken. Tools mit Seiteneffekten, gemeinsamem Zustand oder Anforderungen an die Reihenfolge führst du möglicherweise besser sequenziell aus.

Welche Strategie du auch verwendest: Gib für jeden `tool_use`-Block genau ein `tool_result` zurück, alle zusammen in der nächsten User-Nachricht. Ordne jedes Ergebnis über `tool_use_id` seinem Aufruf zu und platziere jeden `tool_result`-Block vor jeglichem Textinhalt in dieser Nachricht. Die vollständigen Formatierungsregeln findest du unter [Tool-Aufrufe verarbeiten](https://platform.claude.com/docs/de/agents-and-tools/tool-use/handle-tool-calls). Wenn du dich entscheidest, einen bestimmten Aufruf nicht auszuführen (zum Beispiel, weil du den Batch sequenziell ausgeführt hast und ein früherer Aufruf fehlgeschlagen ist), gib trotzdem ein `tool_result` dafür zurück, mit `is_error: true` und einer kurzen Erklärung.

```json
{
  "type": "tool_result",
  "tool_use_id": "toolu_02",
  "is_error": true,
  "content": "Not executed: the preceding write_file call failed."
}
```

Das [Computer-Use-Tool](https://platform.claude.com/docs/de/agents-and-tools/tool-use/computer-use-tool#batch-actions) und das [Browser-Use-Tool](https://platform.claude.com/docs/de/agents-and-tools/tool-use/browser-use-tool#batch-actions) sind strenger. Wenn Claude mehrere ihrer zugehörigen Tool-Aufrufe in einem Turn zurückgibt (eine Batch-Aktion), führe sie sequenziell in der Reihenfolge aus, in der sie erscheinen, und stoppe beim ersten Fehler; jedes Tool definiert den genauen Text, den du für die übersprungenen Aufrufe zurückgeben musst.

## Parallele Tool-Aufrufe testen

<Note>
  **Verwende für die meisten Anwendungen den Tool Runner:** Der [Tool Runner](https://platform.claude.com/docs/de/agents-and-tools/tool-use/tool-runner) des SDK verarbeitet Antworten mit mehreren Tool-Aufrufen und formatiert die Ergebnisse für dich, sodass du diese Verarbeitung nicht selbst schreiben musst. Verwende das manuelle Muster auf dieser Seite, wenn du direkte Kontrolle darüber brauchst, wie die Aufrufe ausgeführt werden, etwa für benutzerdefiniertes Batching, eine bestimmte Reihenfolge oder eigene Fehlerbehandlung.
</Note>

Das folgende Skript sendet eine Anfrage, die parallele Tool-Aufrufe auslösen sollte, überprüft, ob die Antwort sie enthält, und formatiert die Tool-Ergebnisse so, dass die Parallelität weiterhin funktioniert. Führe es mit gesetztem `ANTHROPIC_API_KEY` in deiner Umgebung aus:

<CodeGroup exclude="shell">
  <CodeGroupItem language="cURL">
    Dieser End-to-End-Test erfordert mehr Logik als ein einzelner Shell-Befehl. Verwende das [Claude SDK](https://platform.claude.com/docs/de/cli-sdks-libraries/overview), um ihn auszuführen. Die gesendete Anfrage ist eine Standard-Anfrage zur Tool-Nutzung mit zwei definierten Tools.
  </CodeGroupItem>

  <CodeGroupItem language="CLI">
    Dieser End-to-End-Test erfordert mehr Logik als ein einzelner Shell-Befehl. Verwende das [Claude SDK](https://platform.claude.com/docs/de/cli-sdks-libraries/overview), um ihn auszuführen.
  </CodeGroupItem>

  ```python Python
  client = Anthropic()

  # Tools definieren
  tools = [
      {
          "name": "get_weather",
          "description": "Get the current weather in a given location",
          "input_schema": {
              "type": "object",
              "properties": {
                  "location": {
                      "type": "string",
                      "description": "The city and state, e.g. San Francisco, CA",
                  }
              },
              "required": ["location"],
          },
      },
      {
          "name": "get_time",
          "description": "Get the current time in a given timezone",
          "input_schema": {
              "type": "object",
              "properties": {
                  "timezone": {
                      "type": "string",
                      "description": "The timezone, e.g. America/New_York",
                  }
              },
              "required": ["timezone"],
          },
      },
  ]

  # Konversation mit parallelen Tool-Aufrufen testen
  messages = [
      {
          "role": "user",
          "content": "What's the weather in SF and NYC, and what time is it there?",
      }
  ]

  # Erste Anfrage senden
  print("Requesting parallel tool calls...")
  response = client.messages.create(
      model="claude-opus-5-5", max_tokens=1024, messages=messages, tools=tools
  )

  # Auf parallele Tool-Aufrufe prüfen
  tool_uses = [block for block in response.content if block.type == "tool_use"]
  print(f"\n✓ Claude made {len(tool_uses)} tool calls")

  if len(tool_uses) > 1:
      print("✓ Parallel tool calls detected!")
      for tool in tool_uses:
          print(f"  - {tool.name}: {tool.input}")
  else:
      print("✗ No parallel tool calls detected")

  # Tool-Ausführung simulieren und Ergebnisse korrekt formatieren
  tool_results = []
  for tool_use in tool_uses:
      if tool_use.name == "get_weather":
          if "San Francisco" in str(tool_use.input):
              result = "San Francisco: 68°F, partly cloudy"
          else:
              result = "New York: 45°F, clear skies"
      else:  # get_time
          if "Los_Angeles" in str(tool_use.input):
              result = "2:30 PM PST"
          else:
              result = "5:30 PM EST"

      tool_results.append(
          {"type": "tool_result", "tool_use_id": tool_use.id, "content": result}
      )

  # Konversation mit Tool-Ergebnissen fortsetzen
  messages.extend(
      [
          {"role": "assistant", "content": response.content},
          {"role": "user", "content": tool_results},  # All results in one message!
      ]
  )

  # Finale Antwort abrufen
  print("\nGetting final response...")
  final_response = client.messages.create(
      model="claude-opus-5-5", max_tokens=1024, messages=messages, tools=tools
  )

  final_text = next(
      block.text for block in final_response.content if block.type == "text"
  )
  print(f"\nClaude's response:\n{final_text}")

  # Formatierung überprüfen
  print("\n--- Verification ---")
  print(f"✓ Tool results sent in single user message: {len(tool_results)} results")
  print("✓ No text before tool results in content array")
  print("✓ Conversation formatted correctly for future parallel tool use")
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  // Tools definieren
  const tools: Anthropic.Tool[] = [
    {
      name: "get_weather",
      description: "Get the current weather in a given location",
      input_schema: {
        type: "object" as const,
        properties: {
          location: {
            type: "string",
            description: "The city and state, e.g. San Francisco, CA"
          }
        },
        required: ["location"]
      }
    },
    {
      name: "get_time",
      description: "Get the current time in a given timezone",
      input_schema: {
        type: "object" as const,
        properties: {
          timezone: {
            type: "string",
            description: "The timezone, e.g. America/New_York"
          }
        },
        required: ["timezone"]
      }
    }
  ];

  // Erste Anfrage senden
  console.log("Requesting parallel tool calls...");
  const response = await client.messages.create({
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      {
        role: "user",
        content: "What's the weather in SF and NYC, and what time is it there?"
      }
    ],
    tools: tools
  });

  // Auf parallele Tool-Aufrufe prüfen
  const toolUses = response.content.filter((block) => block.type === "tool_use");
  console.log(`\n✓ Claude made ${toolUses.length} tool calls`);

  if (toolUses.length > 1) {
    console.log("✓ Parallel tool calls detected!");
    for (const tool of toolUses) {
      if (tool.type === "tool_use") {
        console.log(`  - ${tool.name}: ${JSON.stringify(tool.input)}`);
      }
    }
  } else {
    console.log("✗ No parallel tool calls detected");
  }

  // Tool-Ausführung simulieren und Ergebnisse korrekt formatieren
  const toolResults: Anthropic.ToolResultBlockParam[] = toolUses
    .filter((block): block is Anthropic.ToolUseBlock => block.type === "tool_use")
    .map((toolUse) => {
      const input = toolUse.input as Record<string, string>;
      let result: string;
      if (toolUse.name === "get_weather") {
        result = input.location?.includes("San Francisco")
          ? "San Francisco: 68F, partly cloudy"
          : "New York: 45F, clear skies";
      } else {
        result = input.timezone?.includes("Los_Angeles") ? "2:30 PM PST" : "5:30 PM EST";
      }

      return {
        type: "tool_result" as const,
        tool_use_id: toolUse.id,
        content: result
      };
    });

  // Endgültige Antwort mit korrekter Formatierung abrufen
  console.log("\nGetting final response...");
  const finalResponse = await client.messages.create({
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      {
        role: "user",
        content: "What's the weather in SF and NYC, and what time is it there?"
      },
      { role: "assistant", content: response.content },
      { role: "user", content: toolResults }
    ],
    tools: tools
  });

  for (const block of finalResponse.content) {
    if (block.type === "text") {
      console.log(`\nClaude's response:\n${block.text}`);
    }
  }

  // Formatierung überprüfen
  console.log("\n--- Verification ---");
  console.log(`✓ Tool results sent in single user message: ${toolResults.length} results`);
  console.log("✓ No text before tool results in content array");
  console.log("✓ Conversation formatted correctly for future parallel tool use");
  ```

  ```csharp C#
  AnthropicClient client = new();

  var tools = new List<ToolUnion>
  {
      new ToolUnion(new Tool()
      {
          Name = "get_weather",
          Description = "Get the current weather in a given location",
          InputSchema = new InputSchema()
          {
              Properties = new Dictionary<string, JsonElement>
              {
                  ["location"] = JsonSerializer.SerializeToElement(new { type = "string", description = "The city and state, e.g. San Francisco, CA" }),
              },
              Required = ["location"],
          },
      }),
      new ToolUnion(new Tool()
      {
          Name = "get_time",
          Description = "Get the current time in a given timezone",
          InputSchema = new InputSchema()
          {
              Properties = new Dictionary<string, JsonElement>
              {
                  ["timezone"] = JsonSerializer.SerializeToElement(new { type = "string", description = "The timezone, e.g. America/New_York" }),
              },
              Required = ["timezone"],
          },
      }),
  };

  Console.WriteLine("Requesting parallel tool calls...");
  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Messages = [new() { Role = Role.User, Content = "What's the weather in SF and NYC, and what time is it there?" }],
      Tools = tools
  };

  var response = await client.Messages.Create(parameters);

  var toolUses = new List<ToolUseBlock>();
  foreach (var block in response.Content)
  {
      if (block.TryPickToolUse(out var toolUse))
      {
          toolUses.Add(toolUse);
      }
  }
  Console.WriteLine($"\n✓ Claude made {toolUses.Count} tool calls");

  if (toolUses.Count > 1)
  {
      Console.WriteLine("✓ Parallel tool calls detected!");
      foreach (var tool in toolUses)
      {
          Console.WriteLine($"  - {tool.Name}: {JsonSerializer.Serialize(tool.Input)}");
      }
  }
  else
  {
      Console.WriteLine("✗ No parallel tool calls detected");
  }

  var toolResults = new List<ContentBlockParam>();
  foreach (var toolUse in toolUses)
  {
      string result;
      if (toolUse.Name == "get_weather")
      {
          result = JsonSerializer.Serialize(toolUse.Input).Contains("San Francisco")
              ? "San Francisco: 68°F, partly cloudy"
              : "New York: 45°F, clear skies";
      }
      else
      {
          result = JsonSerializer.Serialize(toolUse.Input).Contains("Los_Angeles")
              ? "2:30 PM PST"
              : "5:30 PM EST";
      }

      toolResults.Add(new ContentBlockParam(new ToolResultBlockParam()
      {
          ToolUseID = toolUse.ID,
          Content = result,
      }));
  }

  Console.WriteLine("\nGetting final response...");
  var finalParameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Messages = [
          new() { Role = Role.User, Content = "What's the weather in SF and NYC, and what time is it there?" },
          new() { Role = Role.Assistant, Content = response.Content.Select(block => new ContentBlockParam(block.Json)).ToList() },
          new() { Role = Role.User, Content = new MessageParamContent(toolResults) }
      ],
      Tools = tools
  };

  var finalResponse = await client.Messages.Create(finalParameters);
  var text = finalResponse.Content.Select(b => b.Value).OfType<TextBlock>().FirstOrDefault();
  Console.WriteLine($"\nClaude's response:\n{text?.Text}");

  Console.WriteLine("\n--- Verification ---");
  Console.WriteLine($"✓ Tool results sent in single user message: {toolResults.Count} results");
  Console.WriteLine("✓ No text before tool results in content array");
  Console.WriteLine("✓ Conversation formatted correctly for future parallel tool use");
  ```

  ```go Go
  client := anthropic.NewClient()

  tools := []anthropic.ToolUnionParam{
  	{OfTool: &anthropic.ToolParam{
  		Name:        "get_weather",
  		Description: anthropic.String("Get the current weather in a given location"),
  		InputSchema: anthropic.ToolInputSchemaParam{
  			Properties: map[string]any{
  				"location": map[string]any{
  					"type":        "string",
  					"description": "The city and state, e.g. San Francisco, CA",
  				},
  			},
  			Required: []string{"location"},
  		},
  	}},
  	{OfTool: &anthropic.ToolParam{
  		Name:        "get_time",
  		Description: anthropic.String("Get the current time in a given timezone"),
  		InputSchema: anthropic.ToolInputSchemaParam{
  			Properties: map[string]any{
  				"timezone": map[string]any{
  					"type":        "string",
  					"description": "The timezone, e.g. America/New_York",
  				},
  			},
  			Required: []string{"timezone"},
  		},
  	}},
  }

  fmt.Println("Requesting parallel tool calls...")
  response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("What's the weather in SF and NYC, and what time is it there?")),
  	},
  	Tools: tools,
  })
  if err != nil {
  	log.Fatal(err)
  }

  // Finde Tool-Use-Blöcke per Type-Switch
  type toolUseInfo struct {
  	ID    string
  	Name  string
  	Input json.RawMessage
  }
  var toolUses []toolUseInfo
  for _, block := range response.Content {
  	switch variant := block.AsAny().(type) {
  	case anthropic.ToolUseBlock:
  		toolUses = append(toolUses, toolUseInfo{
  			ID:    variant.ID,
  			Name:  variant.Name,
  			Input: variant.Input,
  		})
  	}
  }

  fmt.Printf("\n✓ Claude made %d tool calls\n", len(toolUses))

  if len(toolUses) > 1 {
  	fmt.Println("✓ Parallel tool calls detected!")
  	for _, tool := range toolUses {
  		fmt.Printf("  - %s: %s\n", tool.Name, string(tool.Input))
  	}
  } else {
  	fmt.Println("✗ No parallel tool calls detected")
  }

  // Erstelle Tool-Ergebnisse
  var toolResults []anthropic.ContentBlockParamUnion
  for _, toolUse := range toolUses {
  	var result string
  	inputStr := string(toolUse.Input)

  	if toolUse.Name == "get_weather" {
  		if strings.Contains(inputStr, "San Francisco") {
  			result = "San Francisco: 68°F, partly cloudy"
  		} else {
  			result = "New York: 45°F, clear skies"
  		}
  	} else {
  		if strings.Contains(inputStr, "Los_Angeles") {
  			result = "2:30 PM PST"
  		} else {
  			result = "5:30 PM EST"
  		}
  	}

  	toolResults = append(toolResults, anthropic.NewToolResultBlock(toolUse.ID, result, false))
  }

  fmt.Println("\nGetting final response...")
  finalResponse, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("What's the weather in SF and NYC, and what time is it there?")),
  		response.ToParam(),
  		anthropic.NewUserMessage(toolResults...),
  	},
  	Tools: tools,
  })
  if err != nil {
  	log.Fatal(err)
  }

  var finalText string
  for _, block := range finalResponse.Content {
  	if textBlock, ok := block.AsAny().(anthropic.TextBlock); ok {
  		finalText = textBlock.Text
  		break
  	}
  }

  fmt.Printf("\nClaude's response:\n%s\n", finalText)

  fmt.Println("\n--- Verification ---")
  fmt.Printf("✓ Tool results sent in single user message: %d results\n", len(toolResults))
  fmt.Println("✓ No text before tool results in content array")
  fmt.Println("✓ Conversation formatted correctly for future parallel tool use")
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  Tool weatherTool = Tool.builder()
      .name("get_weather")
      .description("Get the current weather in a given location")
      .inputSchema(InputSchema.builder()
          .properties(JsonValue.from(Map.of(
              "location", Map.of(
                  "type", "string",
                  "description", "The city and state, e.g. San Francisco, CA"
              )
          )))
          .putAdditionalProperty("required", JsonValue.from(List.of("location")))
          .build())
      .build();

  Tool timeTool = Tool.builder()
      .name("get_time")
      .description("Get the current time in a given timezone")
      .inputSchema(InputSchema.builder()
          .properties(JsonValue.from(Map.of(
              "timezone", Map.of(
                  "type", "string",
                  "description", "The timezone, e.g. America/New_York"
              )
          )))
          .putAdditionalProperty("required", JsonValue.from(List.of("timezone")))
          .build())
      .build();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(1024L)
      .addTool(weatherTool)
      .addTool(timeTool)
      .addUserMessage("What's the weather in SF and NYC, and what time is it there?")
      .build();

  IO.println("Requesting parallel tool calls...");
  Message response = client.messages().create(params);

  List<ToolUseBlock> toolUses = new ArrayList<>();
  for (ContentBlock block : response.content()) {
      if (block.toolUse().isPresent()) {
          toolUses.add(block.toolUse().get());
      }
  }

  IO.println("\n✓ Claude made " + toolUses.size() + " tool calls");

  if (toolUses.size() > 1) {
      IO.println("✓ Parallel tool calls detected!");
      for (ToolUseBlock tool : toolUses) {
          IO.println("  - " + tool.name() + ": " + tool._input());
      }
  } else {
      IO.println("✗ No parallel tool calls detected");
  }

  List<ContentBlockParam> toolResults = new ArrayList<>();
  for (ToolUseBlock toolUse : toolUses) {
      String result;
      if (toolUse.name().equals("get_weather")) {
          String location = toolUse._input().toString();
          result = location.contains("San Francisco")
              ? "San Francisco: 68°F, partly cloudy"
              : "New York: 45°F, clear skies";
      } else {
          String timezone = toolUse._input().toString();
          result = timezone.contains("Los_Angeles")
              ? "2:30 PM PST"
              : "5:30 PM EST";
      }
      toolResults.add(ContentBlockParam.ofToolResult(
          ToolResultBlockParam.builder()
              .toolUseId(toolUse.id())
              .content(result)
              .build()
      ));
  }

  IO.println("\nGetting final response...");
  MessageCreateParams finalParams = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(1024L)
      .addTool(weatherTool)
      .addTool(timeTool)
      .addUserMessage("What's the weather in SF and NYC, and what time is it there?")
      .addMessage(response)
      .addUserMessageOfBlockParams(toolResults)
      .build();

  Message finalResponse = client.messages().create(finalParams);
  finalResponse.content().stream()
      .flatMap(block -> block.text().stream())
      .forEach(textBlock -> IO.println("\nClaude's response:\n" + textBlock.text()));

  IO.println("\n--- Verification ---");
  IO.println("✓ Tool results sent in single user message: " + toolResults.size() + " results");
  IO.println("✓ No text before tool results in content array");
  IO.println("✓ Conversation formatted correctly for future parallel tool use");
  ```

  ```php PHP
  $client = new Client();

  $tools = [
      [
          'name' => 'get_weather',
          'description' => 'Get the current weather in a given location',
          'input_schema' => [
              'type' => 'object',
              'properties' => [
                  'location' => [
                      'type' => 'string',
                      'description' => 'The city and state, e.g. San Francisco, CA'
                  ]
              ],
              'required' => ['location']
          ]
      ],
      [
          'name' => 'get_time',
          'description' => 'Get the current time in a given timezone',
          'input_schema' => [
              'type' => 'object',
              'properties' => [
                  'timezone' => [
                      'type' => 'string',
                      'description' => 'The timezone, e.g. America/New_York'
                  ]
              ],
              'required' => ['timezone']
          ]
      ]
  ];

  echo "Requesting parallel tool calls...\n";
  $response = $client->messages->create(
      maxTokens: 1024,
      messages: [
          ['role' => 'user', 'content' => "What's the weather in SF and NYC, and what time is it there?"]
      ],
      model: 'claude-opus-5-5',
      tools: $tools,
  );

  $toolUses = array_filter($response->content, fn($block) => $block->type === 'tool_use');
  echo "\n✓ Claude made " . count($toolUses) . " tool calls\n";

  if (count($toolUses) > 1) {
      echo "✓ Parallel tool calls detected!\n";
      foreach ($toolUses as $tool) {
          echo "  - {$tool->name}: " . json_encode($tool->input) . "\n";
      }
  } else {
      echo "✗ No parallel tool calls detected\n";
  }

  $toolResults = [];
  foreach ($toolUses as $toolUse) {
      if ($toolUse->name === 'get_weather') {
          $result = str_contains(json_encode($toolUse->input), 'San Francisco')
              ? 'San Francisco: 68°F, partly cloudy'
              : 'New York: 45°F, clear skies';
      } else {
          $result = str_contains(json_encode($toolUse->input), 'Los_Angeles')
              ? '2:30 PM PST'
              : '5:30 PM EST';
      }

      $toolResults[] = [
          'type' => 'tool_result',
          'tool_use_id' => $toolUse->id,
          'content' => $result
      ];
  }

  echo "\nGetting final response...\n";
  $finalResponse = $client->messages->create(
      maxTokens: 1024,
      messages: [
          ['role' => 'user', 'content' => "What's the weather in SF and NYC, and what time is it there?"],
          ['role' => 'assistant', 'content' => $response->content],
          ['role' => 'user', 'content' => $toolResults]
      ],
      model: 'claude-opus-5-5',
      tools: $tools,
  );

  $textBlock = array_find($finalResponse->content, static fn ($block): bool => $block->type === 'text');
  echo "\nClaude's response:\n{$textBlock->text}\n";

  echo "\n--- Verification ---\n";
  echo "✓ Tool results sent in single user message: " . count($toolResults) . " results\n";
  echo "✓ No text before tool results in content array\n";
  echo "✓ Conversation formatted correctly for future parallel tool use\n";
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  tools = [
    {
      name: "get_weather",
      description: "Get the current weather in a given location",
      input_schema: {
        type: "object",
        properties: {
          location: {
            type: "string",
            description: "The city and state, e.g. San Francisco, CA"
          }
        },
        required: ["location"]
      }
    },
    {
      name: "get_time",
      description: "Get the current time in a given timezone",
      input_schema: {
        type: "object",
        properties: {
          timezone: {
            type: "string",
            description: "The timezone, e.g. America/New_York"
          }
        },
        required: ["timezone"]
      }
    }
  ]

  puts "Requesting parallel tool calls..."
  response = client.messages.create(
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      { role: "user", content: "What's the weather in SF and NYC, and what time is it there?" }
    ],
    tools: tools
  )

  tool_uses = response.content.select { |block| block.type == :tool_use }
  puts "\n✓ Claude made #{tool_uses.length} tool calls"

  if tool_uses.length > 1
    puts "✓ Parallel tool calls detected!"
    tool_uses.each do |tool|
      puts "  - #{tool.name}: #{tool.input}"
    end
  else
    puts "✗ No parallel tool calls detected"
  end

  tool_results = tool_uses.map do |tool_use|
    result = if tool_use.name == "get_weather"
      location = tool_use.input[:location].to_s
      location.include?("San Francisco") ? "San Francisco: 68°F, partly cloudy" : "New York: 45°F, clear skies"
    else
      timezone = tool_use.input[:timezone].to_s
      timezone.include?("Los_Angeles") ? "2:30 PM PST" : "5:30 PM EST"
    end

    {
      type: "tool_result",
      tool_use_id: tool_use.id,
      content: result
    }
  end

  puts "\nGetting final response..."
  final_response = client.messages.create(
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [
      { role: "user", content: "What's the weather in SF and NYC, and what time is it there?" },
      { role: "assistant", content: response.content },
      { role: "user", content: tool_results }
    ],
    tools: tools
  )

  final_text = final_response.content.find { |block| block.type == :text }
  puts "\nClaude's response:\n#{final_text.text}"

  puts "\n--- Verification ---"
  puts "✓ Tool results sent in single user message: #{tool_results.length} results"
  puts "✓ No text before tool results in content array"
  puts "✓ Conversation formatted correctly for future parallel tool use"
  ```
</CodeGroup>

Die Zusammenfassungszeilen am Ende wiederholen die beiden Formatierungsregeln, die die Parallelität am Laufen halten: Alle Tool-Ergebnisse werden in einer einzigen User-Nachricht zurückgegeben, und in dieser Nachricht erscheint kein Textinhalt vor den Tool-Ergebnissen.

## Parallele Tool-Nutzung maximieren

Claude 4 und neuere Modelle führen standardmäßig parallele Tool-Aufrufe aus, wenn eine Anfrage von mehreren Tools profitiert. Bei allen Modellen kannst du die Wahrscheinlichkeit paralleler Tool-Aufrufe durch gezieltes Prompting erhöhen:

<AccordionGroup>
  <Accordion title="System-Prompts für parallele Tool-Nutzung">
    Für Claude 4 und neuere Modelle füge Folgendes zu deinem System-Prompt hinzu:

    ```text wrap
    For maximum efficiency, whenever you need to perform multiple independent operations, invoke all relevant tools simultaneously rather than sequentially.
    ```

    Für eine noch stärkere parallele Tool-Nutzung (empfohlen, wenn der Standard nicht ausreicht) verwende:

    ```text wrap
    <use_parallel_tool_calls>
    For maximum efficiency, whenever you perform multiple independent operations, invoke all relevant tools simultaneously rather than sequentially. Prioritize calling tools in parallel whenever possible. For example, when reading 3 files, run 3 tool calls in parallel to read all 3 files into context at the same time. When running multiple read-only commands like `ls` or `list_dir`, always run all of the commands in parallel. Err on the side of maximizing parallel tool calls rather than running too many tools sequentially.
    </use_parallel_tool_calls>
    ```
  </Accordion>

  <Accordion title="Prompting in User-Nachrichten">
    Du kannst parallele Tool-Nutzung auch innerhalb bestimmter User-Nachrichten fördern:

    ```text wrap
    Instead of:
    "What's the weather in Paris? Also check London."

    Use:
    "Check the weather in Paris and London simultaneously."

    Or be explicit:
    "Please use parallel tool calls to get the weather for Paris, London, and Tokyo at the same time."
    ```
  </Accordion>
</AccordionGroup>

<Note>
  **Claude Fable 5.1 in langen Agentenschleifen**

  Claude Fable 5.1 gibt möglicherweise weniger parallele Tool-Aufrufe aus als frühere Modelle, am deutlichsten in langen Agentenschleifen, in denen die nächsten Lesevorgänge nur implizit sind (benutzerdefinierte Coding-Agenten, Bash- und Texteditor-Harnesses, Computer Use). Standardmäßiges Function Calling ist davon nicht betroffen. Welche Batching-Anweisung du hinzufügen solltest und wo sie hingehört, findest du unter [Unabhängige Tool-Aufrufe in Agentenschleifen bündeln](https://platform.claude.com/docs/de/build-with-claude/prompt-engineering/prompting-claude-fable-5-1#batch-independent-tool-calls-in-agent-loops).
</Note>

## Parallele Tool-Nutzung deaktivieren

Parallele Tool-Nutzung ist standardmäßig aktiviert. Um sie auszuschalten, setze `disable_parallel_tool_use: true` innerhalb des [`tool_choice`](https://platform.claude.com/docs/de/agents-and-tools/tool-use/define-tools#forcing-tool-use)-Objekts. Es handelt sich nicht um einen Anfrageparameter auf oberster Ebene. Die Wirkung hängt vom `tool_choice`-Typ ab.

### Höchstens ein Tool-Aufruf

Wenn der `tool_choice`-Typ `auto` ist (der Standard), bedeutet das Setzen von `disable_parallel_tool_use: true`, dass Claude höchstens ein Tool pro Antwort aufruft. Claude kann weiterhin in reinem Text antworten, ohne ein Tool aufzurufen. Die hervorgehobenen Zeilen sind die einzige Änderung gegenüber einer Standardanfrage mit Tool-Nutzung:

<CodeGroup>
  ```bash cURL
  curl https://api.anthropic.com/v1/messages \
    -H "content-type: application/json" \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -d '{
      "model": "claude-opus-5-5",
      "max_tokens": 1024,
      "tools": [{
        "name": "get_weather",
        "description": "Get the current weather in a given location",
        "input_schema": {
          "type": "object",
          "properties": {
            "location": {
              "type": "string",
              "description": "The city and state, e.g. San Francisco, CA"
            }
          },
          "required": ["location"]
        }
      }],
      "tool_choice": {"type": "auto", "disable_parallel_tool_use": true},
      "messages": [
        {"role": "user", "content": "What is the weather in San Francisco and New York?"}
      ]
    }'
  ```

  ```bash CLI
  ant messages create <<'YAML'
  model: claude-opus-5-5
  max_tokens: 1024
  tools:
    - name: get_weather
      description: Get the current weather in a given location
      input_schema:
        type: object
        properties:
          location:
            type: string
            description: The city and state, e.g. San Francisco, CA
        required: [location]
  tool_choice:
    type: auto
    disable_parallel_tool_use: true
  messages:
    - role: user
      content: What is the weather in San Francisco and New York?
  YAML
  ```

  ```python Python
  client = Anthropic()

  response = client.messages.create(
      model="claude-opus-5-5",
      max_tokens=1024,
      tools=[
          {
              "name": "get_weather",
              "description": "Get the current weather in a given location",
              "input_schema": {
                  "type": "object",
                  "properties": {
                      "location": {
                          "type": "string",
                          "description": "The city and state, e.g. San Francisco, CA",
                      }
                  },
                  "required": ["location"],
              },
          }
      ],
      tool_choice={"type": "auto", "disable_parallel_tool_use": True},
      messages=[
          {
              "role": "user",
              "content": "What is the weather in San Francisco and New York?",
          }
      ],
  )
  print(response.content)
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  const response = await client.messages.create({
    model: "claude-opus-5-5",
    max_tokens: 1024,
    tools: [
      {
        name: "get_weather",
        description: "Get the current weather in a given location",
        input_schema: {
          type: "object",
          properties: {
            location: {
              type: "string",
              description: "The city and state, e.g. San Francisco, CA"
            }
          },
          required: ["location"]
        }
      }
    ],
    tool_choice: { type: "auto", disable_parallel_tool_use: true },
    messages: [{ role: "user", content: "What is the weather in San Francisco and New York?" }]
  });
  console.log(response.content);
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Tools = [
          new ToolUnion(new Tool()
          {
              Name = "get_weather",
              Description = "Get the current weather in a given location",
              InputSchema = new InputSchema()
              {
                  Properties = new Dictionary<string, JsonElement>
                  {
                      ["location"] = JsonSerializer.SerializeToElement(new { type = "string", description = "The city and state, e.g. San Francisco, CA" }),
                  },
                  Required = ["location"],
              },
          }),
      ],
      ToolChoice = new ToolChoiceAuto { DisableParallelToolUse = true },
      Messages = [new() { Role = Role.User, Content = "What is the weather in San Francisco and New York?" }]
  };

  var response = await client.Messages.Create(parameters);
  Console.WriteLine(response);
  ```

  ```go Go
  client := anthropic.NewClient()

  response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Tools: []anthropic.ToolUnionParam{
  		{OfTool: &anthropic.ToolParam{
  			Name:        "get_weather",
  			Description: anthropic.String("Get the current weather in a given location"),
  			InputSchema: anthropic.ToolInputSchemaParam{
  				Properties: map[string]any{
  					"location": map[string]any{
  						"type":        "string",
  						"description": "The city and state, e.g. San Francisco, CA",
  					},
  				},
  				Required: []string{"location"},
  			},
  		}},
  	},
  	ToolChoice: anthropic.ToolChoiceUnionParam{
  		OfAuto: &anthropic.ToolChoiceAutoParam{
  			DisableParallelToolUse: anthropic.Bool(true),
  		},
  	},
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("What is the weather in San Francisco and New York?")),
  	},
  })
  if err != nil {
  	log.Fatal(err)
  }
  fmt.Println(response.Content)
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  InputSchema schema = InputSchema.builder()
      .properties(
          JsonValue.from(
              Map.of(
                  "location", Map.of(
                      "type", "string",
                      "description", "The city and state, e.g. San Francisco, CA"
                  )
              )
          )
      )
      .putAdditionalProperty("required", JsonValue.from(List.of("location")))
      .build();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(1024L)
      .addTool(
          Tool.builder()
              .name("get_weather")
              .description("Get the current weather in a given location")
              .inputSchema(schema)
              .build()
      )
      .toolChoice(ToolChoiceAuto.builder().disableParallelToolUse(true).build())
      .addUserMessage("What is the weather in San Francisco and New York?")
      .build();

  Message response = client.messages().create(params);
  IO.println(response.content());
  ```

  ```php PHP
  $client = new Client();

  $response = $client->messages->create(
      maxTokens: 1024,
      messages: [
          ['role' => 'user', 'content' => 'What is the weather in San Francisco and New York?']
      ],
      model: 'claude-opus-5-5',
      toolChoice: ['type' => 'auto', 'disableParallelToolUse' => true],
      tools: [
          [
              'name' => 'get_weather',
              'description' => 'Get the current weather in a given location',
              'input_schema' => [
                  'type' => 'object',
                  'properties' => [
                      'location' => [
                          'type' => 'string',
                          'description' => 'The city and state, e.g. San Francisco, CA'
                      ]
                  ],
                  'required' => ['location']
              ]
          ]
      ],
  );

  echo $response;
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  response = client.messages.create(
    model: "claude-opus-5-5",
    max_tokens: 1024,
    tools: [
      {
        name: "get_weather",
        description: "Get the current weather in a given location",
        input_schema: {
          type: "object",
          properties: {
            location: {
              type: "string",
              description: "The city and state, e.g. San Francisco, CA"
            }
          },
          required: ["location"]
        }
      }
    ],
    tool_choice: { type: "auto", disable_parallel_tool_use: true },
    messages: [
      { role: "user", content: "What is the weather in San Francisco and New York?" }
    ]
  )
  puts response.content
  ```
</CodeGroup>

### Genau ein Tool-Aufruf

Wenn der `tool_choice`-Typ `any` oder `tool` ist, bedeutet das Setzen von `disable_parallel_tool_use: true`, dass Claude genau ein Tool aufruft. Claude Opus 5.5, Claude Sonnet 5.5, Claude Fable 5.1 und Claude Mythos 5.1 unterstützen diese `tool_choice`-Typen nicht (siehe [Tool-Nutzung erzwingen](https://platform.claude.com/docs/de/agents-and-tools/tool-use/define-tools#forcing-tool-use)). Das folgende Beispiel verwendet `any`. Dasselbe Feld funktioniert auch mit `tool`:

<CodeGroup>
  ```bash cURL
  curl https://api.anthropic.com/v1/messages \
    -H "content-type: application/json" \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -d '{
      "model": "claude-opus-5",
      "max_tokens": 1024,
      "tools": [{
        "name": "get_weather",
        "description": "Get the current weather in a given location",
        "input_schema": {
          "type": "object",
          "properties": {
            "location": {
              "type": "string",
              "description": "The city and state, e.g. San Francisco, CA"
            }
          },
          "required": ["location"]
        }
      }],
      "tool_choice": {"type": "any", "disable_parallel_tool_use": true},
      "messages": [
        {"role": "user", "content": "What is the weather in San Francisco and New York?"}
      ]
    }'
  ```

  ```bash CLI
  ant messages create <<'YAML'
  model: claude-opus-5
  max_tokens: 1024
  tools:
    - name: get_weather
      description: Get the current weather in a given location
      input_schema:
        type: object
        properties:
          location:
            type: string
            description: The city and state, e.g. San Francisco, CA
        required: [location]
  tool_choice:
    type: any
    disable_parallel_tool_use: true
  messages:
    - role: user
      content: What is the weather in San Francisco and New York?
  YAML
  ```

  ```python Python
  client = Anthropic()

  response = client.messages.create(
      model="claude-opus-5",
      max_tokens=1024,
      tools=[
          {
              "name": "get_weather",
              "description": "Get the current weather in a given location",
              "input_schema": {
                  "type": "object",
                  "properties": {
                      "location": {
                          "type": "string",
                          "description": "The city and state, e.g. San Francisco, CA",
                      }
                  },
                  "required": ["location"],
              },
          }
      ],
      tool_choice={"type": "any", "disable_parallel_tool_use": True},
      messages=[
          {
              "role": "user",
              "content": "What is the weather in San Francisco and New York?",
          }
      ],
  )
  print(response.content)
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  const response = await client.messages.create({
    model: "claude-opus-5",
    max_tokens: 1024,
    tools: [
      {
        name: "get_weather",
        description: "Get the current weather in a given location",
        input_schema: {
          type: "object",
          properties: {
            location: {
              type: "string",
              description: "The city and state, e.g. San Francisco, CA"
            }
          },
          required: ["location"]
        }
      }
    ],
    tool_choice: { type: "any", disable_parallel_tool_use: true },
    messages: [{ role: "user", content: "What is the weather in San Francisco and New York?" }]
  });
  console.log(response.content);
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5,
      MaxTokens = 1024,
      Tools = [
          new ToolUnion(new Tool()
          {
              Name = "get_weather",
              Description = "Get the current weather in a given location",
              InputSchema = new InputSchema()
              {
                  Properties = new Dictionary<string, JsonElement>
                  {
                      ["location"] = JsonSerializer.SerializeToElement(new { type = "string", description = "The city and state, e.g. San Francisco, CA" }),
                  },
                  Required = ["location"],
              },
          }),
      ],
      ToolChoice = new ToolChoiceAny { DisableParallelToolUse = true },
      Messages = [new() { Role = Role.User, Content = "What is the weather in San Francisco and New York?" }]
  };

  var response = await client.Messages.Create(parameters);
  Console.WriteLine(response);
  ```

  ```go Go
  client := anthropic.NewClient()

  response, err := client.Messages.New(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5,
  	MaxTokens: 1024,
  	Tools: []anthropic.ToolUnionParam{
  		{OfTool: &anthropic.ToolParam{
  			Name:        "get_weather",
  			Description: anthropic.String("Get the current weather in a given location"),
  			InputSchema: anthropic.ToolInputSchemaParam{
  				Properties: map[string]any{
  					"location": map[string]any{
  						"type":        "string",
  						"description": "The city and state, e.g. San Francisco, CA",
  					},
  				},
  				Required: []string{"location"},
  			},
  		}},
  	},
  	ToolChoice: anthropic.ToolChoiceUnionParam{
  		OfAny: &anthropic.ToolChoiceAnyParam{
  			DisableParallelToolUse: anthropic.Bool(true),
  		},
  	},
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("What is the weather in San Francisco and New York?")),
  	},
  })
  if err != nil {
  	log.Fatal(err)
  }
  fmt.Println(response.Content)
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  InputSchema schema = InputSchema.builder()
      .properties(
          JsonValue.from(
              Map.of(
                  "location", Map.of(
                      "type", "string",
                      "description", "The city and state, e.g. San Francisco, CA"
                  )
              )
          )
      )
      .putAdditionalProperty("required", JsonValue.from(List.of("location")))
      .build();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5)
      .maxTokens(1024L)
      .addTool(
          Tool.builder()
              .name("get_weather")
              .description("Get the current weather in a given location")
              .inputSchema(schema)
              .build()
      )
      .toolChoice(ToolChoiceAny.builder().disableParallelToolUse(true).build())
      .addUserMessage("What is the weather in San Francisco and New York?")
      .build();

  Message response = client.messages().create(params);
  IO.println(response.content());
  ```

  ```php PHP
  $client = new Client();

  $response = $client->messages->create(
      maxTokens: 1024,
      messages: [
          ['role' => 'user', 'content' => 'What is the weather in San Francisco and New York?']
      ],
      model: 'claude-opus-5',
      toolChoice: ['type' => 'any', 'disableParallelToolUse' => true],
      tools: [
          [
              'name' => 'get_weather',
              'description' => 'Get the current weather in a given location',
              'input_schema' => [
                  'type' => 'object',
                  'properties' => [
                      'location' => [
                          'type' => 'string',
                          'description' => 'The city and state, e.g. San Francisco, CA'
                      ]
                  ],
                  'required' => ['location']
              ]
          ]
      ],
  );

  echo $response;
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  response = client.messages.create(
    model: "claude-opus-5",
    max_tokens: 1024,
    tools: [
      {
        name: "get_weather",
        description: "Get the current weather in a given location",
        input_schema: {
          type: "object",
          properties: {
            location: {
              type: "string",
              description: "The city and state, e.g. San Francisco, CA"
            }
          },
          required: ["location"]
        }
      }
    ],
    tool_choice: { type: "any", disable_parallel_tool_use: true },
    messages: [
      { role: "user", content: "What is the weather in San Francisco and New York?" }
    ]
  )
  puts response.content
  ```
</CodeGroup>

## Fehlerbehebung

Wenn Claude nicht wie erwartet parallele Tool-Aufrufe ausführt, prüfe diese häufigen Probleme:

**1. Falsche Formatierung der Tool-Ergebnisse**

Das häufigste Problem ist eine falsche Formatierung der Tool-Ergebnisse im Gesprächsverlauf. Das „lehrt“ Claude, parallele Aufrufe zu vermeiden.

Speziell für parallele Tool-Nutzung:

* **Falsch:** eine separate User-Nachricht für jedes Tool-Ergebnis
* **Richtig:** alle Tool-Ergebnisse zusammen in einer einzigen User-Nachricht

```json
// Wrong: separate user messages reduce parallel tool use
[
  {"role": "assistant", "content": [tool_use_1, tool_use_2]},
  {"role": "user", "content": [tool_result_1]},
  {"role": "user", "content": [tool_result_2]}  // Separate message
]

// Correct: one user message with all results maintains parallel tool use
[
  {"role": "assistant", "content": [tool_use_1, tool_use_2]},
  {"role": "user", "content": [tool_result_1, tool_result_2]}  // Single message
]
```

Weitere Formatierungsregeln findest du unter [Tool-Aufrufe verarbeiten](https://platform.claude.com/docs/de/agents-and-tools/tool-use/handle-tool-calls).

**2. Schwaches Prompting**

Das Standard-Prompting reicht möglicherweise nicht aus. Verwende den stärkeren System-Prompt aus [Parallele Tool-Nutzung maximieren](https://platform.claude.com/docs/de/agents-and-tools/tool-use/parallel-tool-use#maximizing-parallel-tool-use).

**3. Parallele Tool-Nutzung messen**

Um zu überprüfen, ob parallele Tool-Aufrufe funktionieren:

<CodeGroup exclude="shell">
  <CodeGroupItem language="cURL">
    Um die parallele Tool-Nutzung zu messen, analysiert dein Code die Antworten, die er bereits gesammelt hat. Das erfordert mehr Logik als ein einzelner Shell-Befehl. Verwende dafür das [Claude SDK](https://platform.claude.com/docs/de/cli-sdks-libraries/overview).
  </CodeGroupItem>

  <CodeGroupItem language="CLI">
    Um die parallele Tool-Nutzung zu messen, analysiert dein Code die Antworten, die er bereits gesammelt hat. Das erfordert mehr Logik als ein einzelner Shell-Befehl. Verwende dafür das [Claude SDK](https://platform.claude.com/docs/de/cli-sdks-libraries/overview).
  </CodeGroupItem>

  ```python Python
  messages = []  # Message objects returned by client.messages.create across your run

  tool_call_messages = [
      msg for msg in messages if any(block.type == "tool_use" for block in msg.content)
  ]
  total_tool_calls = sum(
      len([block for block in msg.content if block.type == "tool_use"])
      for msg in tool_call_messages
  )
  avg_tools_per_message = (
      total_tool_calls / len(tool_call_messages) if tool_call_messages else 0.0
  )
  print(f"Average tools per message: {avg_tools_per_message}")
  # Sollte > 1,0 sein, wenn parallele Aufrufe funktionieren
  ```

  ```typescript TypeScript
  const messages: Anthropic.Message[] = []; // Message objects returned by client.messages.create across your run

  const toolCallMessages = messages.filter((message) =>
    message.content.some((block) => block.type === "tool_use")
  );
  const totalToolCalls = toolCallMessages.reduce(
    (sum, message) => sum + message.content.filter((block) => block.type === "tool_use").length,
    0
  );
  const avgToolsPerMessage =
    toolCallMessages.length > 0 ? totalToolCalls / toolCallMessages.length : 0;
  console.log(`Average tools per message: ${avgToolsPerMessage}`);
  // Sollte > 1,0 sein, wenn parallele Aufrufe funktionieren
  ```

  ```csharp C#
  List<Message> messages = []; // Message objects returned by client.Messages.Create across your run

  var toolCallMessages = messages
      .Where(message => message.Content.Any(block => block.TryPickToolUse(out _)))
      .ToList();
  var totalToolCalls = toolCallMessages
      .Sum(message => message.Content.Count(block => block.TryPickToolUse(out _)));
  var avgToolsPerMessage = toolCallMessages.Count > 0 ? (double)totalToolCalls / toolCallMessages.Count : 0.0;
  Console.WriteLine($"Average tools per message: {avgToolsPerMessage}");
  // Sollte > 1,0 sein, wenn parallele Aufrufe funktionieren
  ```

  ```go Go
  var messages []anthropic.Message // Message values returned by client.Messages.New across your run

  toolCallMessageCount := 0
  totalToolCalls := 0
  for _, message := range messages {
  	callsInMessage := 0
  	for _, block := range message.Content {
  		if block.Type == "tool_use" {
  			callsInMessage++
  		}
  	}
  	if callsInMessage > 0 {
  		toolCallMessageCount++
  		totalToolCalls += callsInMessage
  	}
  }

  avgToolsPerMessage := 0.0
  if toolCallMessageCount > 0 {
  	avgToolsPerMessage = float64(totalToolCalls) / float64(toolCallMessageCount)
  }
  fmt.Println("Average tools per message:", avgToolsPerMessage)
  // Sollte > 1,0 sein, wenn parallele Aufrufe funktionieren
  ```

  ```java Java
  List<Message> messages = List.of(); // Message objects returned by client.messages().create() across your run

  List<Message> toolCallMessages = messages.stream()
      .filter(message -> message.content().stream().anyMatch(ContentBlock::isToolUse))
      .toList();
  long totalToolCalls = toolCallMessages.stream()
      .mapToLong(message -> message.content().stream().filter(ContentBlock::isToolUse).count())
      .sum();
  double avgToolsPerMessage = toolCallMessages.isEmpty() ? 0.0 : (double) totalToolCalls / toolCallMessages.size();
  IO.println("Average tools per message: " + avgToolsPerMessage);
  // Sollte > 1,0 sein, wenn parallele Aufrufe funktionieren
  ```

  ```php PHP
  // $messages: Message-Objekte, die von $client->messages->create() während deines Durchlaufs zurückgegeben wurden
  $messages = [];

  $toolCallMessages = array_values(array_filter(
      $messages,
      fn ($message) => count(array_filter($message->content, fn ($block) => $block->type === 'tool_use')) > 0
  ));
  $totalToolCalls = array_sum(array_map(
      fn ($message) => count(array_filter($message->content, fn ($block) => $block->type === 'tool_use')),
      $toolCallMessages
  ));
  $avgToolsPerMessage = count($toolCallMessages) > 0 ? $totalToolCalls / count($toolCallMessages) : 0.0;
  echo "Average tools per message: {$avgToolsPerMessage}\n";
  // Sollte > 1,0 sein, wenn parallele Aufrufe funktionieren
  ```

  ```ruby Ruby
  messages = [] # Message objects returned by client.messages.create across your run

  tool_call_messages = messages.select { |message| message.content.any? { |block| block.type == :tool_use } }
  total_tool_calls = tool_call_messages.sum { |message| message.content.count { |block| block.type == :tool_use } }
  avg_tools_per_message = tool_call_messages.empty? ? 0.0 : total_tool_calls.to_f / tool_call_messages.size
  puts "Average tools per message: #{avg_tools_per_message}"
  # Sollte > 1,0 sein, wenn parallele Aufrufe funktionieren
  ```
</CodeGroup>

**4. Aufrufe in einem Batch scheinen voneinander abzuhängen**

Die Ausführungsreihenfolge ist deine Wahl. Wenn deine Tools Abhängigkeiten in der Reihenfolge haben, ist es eine gültige Strategie, den Batch sequenziell auszuführen und beim ersten Fehler zu stoppen (und die vorgeschriebene für die Tools [Computer Use](https://platform.claude.com/docs/de/agents-and-tools/tool-use/computer-use-tool#batch-actions) und [Browser Use](https://platform.claude.com/docs/de/agents-and-tools/tool-use/browser-use-tool#batch-actions)): Gib `is_error: true` für jeden Aufruf zurück, den du nicht ausgeführt hast. Wenn du parallel ausführst und ein Aufruf fehlschlägt, weil seine Voraussetzung noch nicht abgeschlossen war, gib `is_error: true` mit der natürlichen Fehlermeldung zurück. Claude wird den Aufruf im nächsten Turn erneut ausgeben. Um zu verringern, dass abhängige Aufrufe gemeinsam erscheinen, füge Folgendes zu deinem System-Prompt hinzu: „Only batch tool calls that are independent of each other.“

## Nächste Schritte

<CardGroup cols={3}>
  <Card title="Tool Runner (SDK)" icon="wrench" href="https://platform.claude.com/docs/de/agents-and-tools/tool-use/tool-runner">
    Verwende die Tool-Runner-Abstraktion des SDK, um die Agentenschleife, das Error-Wrapping und die Typsicherheit automatisch zu handhaben.
  </Card>

  <Card title="Tool-Aufrufe verarbeiten" icon="arrows-left-right" href="https://platform.claude.com/docs/de/agents-and-tools/tool-use/handle-tool-calls">
    Parse tool\_use-Blöcke, formatiere tool\_result-Antworten und behandle Fehler mit is\_error.
  </Card>

  <Card title="Tools definieren" icon="hammer" href="https://platform.claude.com/docs/de/agents-and-tools/tool-use/define-tools">
    Lege Tool-Schemas fest, schreibe wirksame Beschreibungen und steuere, wann Claude deine Tools aufruft.
  </Card>
</CardGroup>