Constructor Detail

Method Detail

• maxTokens

   final MessageCreateParams.Body.Builder maxTokens(Long maxTokens)

  The maximum number of tokens to generate before stopping.

  Note that our models may stop before reaching this maximum. This parameter only specifies the absolute maximum number of tokens to generate.

  Different models have different maximum values for this parameter. See models for details.

• maxTokens

   final MessageCreateParams.Body.Builder maxTokens(JsonField<Long> maxTokens)

  Sets Builder.maxTokens to an arbitrary JSON value.

  You should usually call Builder.maxTokens with a well-typed Long value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• messages

   final MessageCreateParams.Body.Builder messages(List<MessageParam> messages)

  Input messages.

  Our models are trained to operate on alternating user and assistant conversational turns. When creating a new Message, you specify the prior conversational turns with the messages parameter, and the model then generates the next Message in the conversation. Consecutive user or assistant turns in your request will be combined into a single turn.

  Each input message must be an object with a role and content. You can specify a single user-role message, or you can include multiple user and assistant messages.

  If the final message uses the assistant role, the response content will continue immediately from the content in that message. This can be used to constrain part of the model's response.

  Example with a single user message:

  [{"role": "user", "content": "Hello, Claude"}]

  Example with multiple conversational turns:

  [
    {"role": "user", "content": "Hello there."},
    {"role": "assistant", "content": "Hi, I'm Claude. How can I help you?"},
    {"role": "user", "content": "Can you explain LLMs in plain English?"},
  ]

  Example with a partially-filled response from Claude:

  [
    {"role": "user", "content": "What's the Greek name for Sun? (A) Sol (B) Helios (C) Sun"},
    {"role": "assistant", "content": "The best answer is ("},
  ]

  Each input message content may be either a single string or an array of content blocks, where each block has a specific type. Using a string for content is shorthand for an array of one content block of type "text". The following input messages are equivalent:

  {"role": "user", "content": "Hello, Claude"}

  {"role": "user", "content": [{"type": "text", "text": "Hello, Claude"}]}

  See input examples.

  Note that if you want to include a system prompt, you can use the top-level system parameter — there is no "system" role for input messages in the Messages API.

  There is a limit of 100,000 messages in a single request.

• messages

   final MessageCreateParams.Body.Builder messages(JsonField<List<MessageParam>> messages)

  Sets Builder.messages to an arbitrary JSON value.

  You should usually call Builder.messages with a well-typed List<MessageParam> value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• addMessage

   final MessageCreateParams.Body.Builder addMessage(MessageParam message)

  Adds a single MessageParam to messages.

• addMessage

   final MessageCreateParams.Body.Builder addMessage(Message message)

  Alias for calling addMessage with message.toParam().

• addUserMessage

   final MessageCreateParams.Body.Builder addUserMessage(MessageParam.Content content)

  Alias for calling addMessage with the following:

  MessageParam.builder()
      .role(MessageParam.Role.USER)
      .content(content)
      .build()

• addUserMessage

   final MessageCreateParams.Body.Builder addUserMessage(String string)

  Alias for calling addUserMessage with MessageParam.Content.ofString(string).

• addUserMessageOfBlockParams

   final MessageCreateParams.Body.Builder addUserMessageOfBlockParams(List<ContentBlockParam> blockParams)

  Alias for calling addUserMessage with MessageParam.Content.ofBlockParams(blockParams).

• addAssistantMessage

   final MessageCreateParams.Body.Builder addAssistantMessage(MessageParam.Content content)

  Alias for calling addMessage with the following:

  MessageParam.builder()
      .role(MessageParam.Role.ASSISTANT)
      .content(content)
      .build()

• addAssistantMessage

   final MessageCreateParams.Body.Builder addAssistantMessage(String string)

  Alias for calling addAssistantMessage with MessageParam.Content.ofString(string).

• addAssistantMessageOfBlockParams

   final MessageCreateParams.Body.Builder addAssistantMessageOfBlockParams(List<ContentBlockParam> blockParams)

  Alias for calling addAssistantMessage with MessageParam.Content.ofBlockParams(blockParams).

• model

   final MessageCreateParams.Body.Builder model(Model model)

  The model that will complete your prompt.\n\nSee models for additional details and options.

• model

   final MessageCreateParams.Body.Builder model(JsonField<Model> model)

  Sets Builder.model to an arbitrary JSON value.

  You should usually call Builder.model with a well-typed Model value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• model

   final MessageCreateParams.Body.Builder model(String value)

  Sets model to an arbitrary String.

  You should usually call model with a well-typed Model constant instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• cacheControl

   final MessageCreateParams.Body.Builder cacheControl(CacheControlEphemeral cacheControl)

  Top-level cache control automatically applies a cache_control marker to the last cacheable block in the request.

• cacheControl

   final MessageCreateParams.Body.Builder cacheControl(Optional<CacheControlEphemeral> cacheControl)

  Alias for calling Builder.cacheControl with cacheControl.orElse(null).

• cacheControl

   final MessageCreateParams.Body.Builder cacheControl(JsonField<CacheControlEphemeral> cacheControl)

  Sets Builder.cacheControl to an arbitrary JSON value.

  You should usually call Builder.cacheControl with a well-typed CacheControlEphemeral value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• container

   final MessageCreateParams.Body.Builder container(String container)

  Container identifier for reuse across requests.

• container

   final MessageCreateParams.Body.Builder container(Optional<String> container)

  Alias for calling Builder.container with container.orElse(null).

• container

   final MessageCreateParams.Body.Builder container(JsonField<String> container)

  Sets Builder.container to an arbitrary JSON value.

  You should usually call Builder.container with a well-typed String value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• inferenceGeo

   final MessageCreateParams.Body.Builder inferenceGeo(String inferenceGeo)

  Specifies the geographic region for inference processing. If not specified, the workspace's default_inference_geo is used.

• inferenceGeo

   final MessageCreateParams.Body.Builder inferenceGeo(Optional<String> inferenceGeo)

  Alias for calling Builder.inferenceGeo with inferenceGeo.orElse(null).

• inferenceGeo

   final MessageCreateParams.Body.Builder inferenceGeo(JsonField<String> inferenceGeo)

  Sets Builder.inferenceGeo to an arbitrary JSON value.

  You should usually call Builder.inferenceGeo with a well-typed String value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• metadata

   final MessageCreateParams.Body.Builder metadata(Metadata metadata)

  An object describing metadata about the request.

• metadata

   final MessageCreateParams.Body.Builder metadata(JsonField<Metadata> metadata)

  Sets Builder.metadata to an arbitrary JSON value.

  You should usually call Builder.metadata with a well-typed Metadata value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• outputConfig

   final MessageCreateParams.Body.Builder outputConfig(OutputConfig outputConfig)

  Configuration options for the model's output, such as the output format.

• outputConfig

   final MessageCreateParams.Body.Builder outputConfig(JsonField<OutputConfig> outputConfig)

  Sets Builder.outputConfig to an arbitrary JSON value.

  You should usually call Builder.outputConfig with a well-typed OutputConfig value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• serviceTier

   final MessageCreateParams.Body.Builder serviceTier(MessageCreateParams.ServiceTier serviceTier)

  Determines whether to use priority capacity (if available) or standard capacity for this request.

  Anthropic offers different levels of service for your API requests. See service-tiers for details.

• serviceTier

   final MessageCreateParams.Body.Builder serviceTier(JsonField<MessageCreateParams.ServiceTier> serviceTier)

  Sets Builder.serviceTier to an arbitrary JSON value.

  You should usually call Builder.serviceTier with a well-typed ServiceTier value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• stopSequences

   final MessageCreateParams.Body.Builder stopSequences(List<String> stopSequences)

  Custom text sequences that will cause the model to stop generating.

  Our models will normally stop when they have naturally completed their turn, which will result in a response stop_reason of "end_turn".

  If you want the model to stop generating when it encounters custom strings of text, you can use the stop_sequences parameter. If the model encounters one of the custom sequences, the response stop_reason value will be "stop_sequence" and the response stop_sequence value will contain the matched stop sequence.

• stopSequences

   final MessageCreateParams.Body.Builder stopSequences(JsonField<List<String>> stopSequences)

  Sets Builder.stopSequences to an arbitrary JSON value.

  You should usually call Builder.stopSequences with a well-typed List<String> value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• addStopSequence

   final MessageCreateParams.Body.Builder addStopSequence(String stopSequence)

  Adds a single String to stopSequences.

• system

   final MessageCreateParams.Body.Builder system(MessageCreateParams.System system)

  System prompt.

  A system prompt is a way of providing context and instructions to Claude, such as specifying a particular goal or role. See our guide to system prompts.

• system

   final MessageCreateParams.Body.Builder system(JsonField<MessageCreateParams.System> system)

  Sets Builder.system to an arbitrary JSON value.

  You should usually call Builder.system with a well-typed System value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• system

   final MessageCreateParams.Body.Builder system(String string)

  Alias for calling system with System.ofString(string).

• systemOfTextBlockParams

   final MessageCreateParams.Body.Builder systemOfTextBlockParams(List<TextBlockParam> textBlockParams)

  Alias for calling system with System.ofTextBlockParams(textBlockParams).

• temperature

   final MessageCreateParams.Body.Builder temperature(Double temperature)

  Amount of randomness injected into the response.

  Defaults to 1.0. Ranges from 0.0 to 1.0. Use temperature closer to 0.0 for analytical / multiple choice, and closer to 1.0 for creative and generative tasks.

  Note that even with temperature of 0.0, the results will not be fully deterministic.

• temperature

   final MessageCreateParams.Body.Builder temperature(JsonField<Double> temperature)

  Sets Builder.temperature to an arbitrary JSON value.

  You should usually call Builder.temperature with a well-typed Double value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• thinking

   final MessageCreateParams.Body.Builder thinking(ThinkingConfigParam thinking)

  Configuration for enabling Claude's extended thinking.

  When enabled, responses include thinking content blocks showing Claude's thinking process before the final answer. Requires a minimum budget of 1,024 tokens and counts towards your max_tokens limit.

  See extended thinking for details.

• thinking

   final MessageCreateParams.Body.Builder thinking(JsonField<ThinkingConfigParam> thinking)

  Sets Builder.thinking to an arbitrary JSON value.

  You should usually call Builder.thinking with a well-typed ThinkingConfigParam value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• thinking

   final MessageCreateParams.Body.Builder thinking(ThinkingConfigEnabled enabled)

  Alias for calling thinking with ThinkingConfigParam.ofEnabled(enabled).

• thinking

   final MessageCreateParams.Body.Builder thinking(ThinkingConfigDisabled disabled)

  Alias for calling thinking with ThinkingConfigParam.ofDisabled(disabled).

• thinking

   final MessageCreateParams.Body.Builder thinking(ThinkingConfigAdaptive adaptive)

  Alias for calling thinking with ThinkingConfigParam.ofAdaptive(adaptive).

• enabledThinking

   final MessageCreateParams.Body.Builder enabledThinking(Long budgetTokens)

  Alias for calling thinking with the following:

  ThinkingConfigEnabled.builder()
      .budgetTokens(budgetTokens)
      .build()

• toolChoice

   final MessageCreateParams.Body.Builder toolChoice(ToolChoice toolChoice)

  How the model should use the provided tools. The model can use a specific tool, any available tool, decide by itself, or not use tools at all.

• toolChoice

   final MessageCreateParams.Body.Builder toolChoice(JsonField<ToolChoice> toolChoice)

  Sets Builder.toolChoice to an arbitrary JSON value.

  You should usually call Builder.toolChoice with a well-typed ToolChoice value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• toolChoice

   final MessageCreateParams.Body.Builder toolChoice(ToolChoiceAuto auto)

  Alias for calling toolChoice with ToolChoice.ofAuto(auto).

• toolChoice

   final MessageCreateParams.Body.Builder toolChoice(ToolChoiceAny any)

  Alias for calling toolChoice with ToolChoice.ofAny(any).

• toolChoice

   final MessageCreateParams.Body.Builder toolChoice(ToolChoiceTool tool)

  Alias for calling toolChoice with ToolChoice.ofTool(tool).

• toolChoice

   final MessageCreateParams.Body.Builder toolChoice(ToolChoiceNone none)

  Alias for calling toolChoice with ToolChoice.ofNone(none).

• toolToolChoice

   final MessageCreateParams.Body.Builder toolToolChoice(String name)

  Alias for calling toolChoice with the following:

  ToolChoiceTool.builder()
      .name(name)
      .build()

• tools

   final MessageCreateParams.Body.Builder tools(List<ToolUnion> tools)

  Definitions of tools that the model may use.

  If you include tools in your API request, the model may return tool_use content blocks that represent the model's use of those tools. You can then run those tools using the tool input generated by the model and then optionally return results back to the model using tool_result content blocks.

  There are two types of tools: client tools and server tools. The behavior described below applies to client tools. For server tools, see their individual documentation as each has its own behavior (e.g., the web search tool).

  Each tool definition includes:

  • name: Name of the tool.

  • description: Optional, but strongly-recommended description of the tool.

  • input_schema: JSON schema for the tool input shape that the model will produce in tool_use output content blocks.

  For example, if you defined tools as:

  [
    {
      "name": "get_stock_price",
      "description": "Get the current stock price for a given ticker symbol.",
      "input_schema": {
        "type": "object",
        "properties": {
          "ticker": {
            "type": "string",
            "description": "The stock ticker symbol, e.g. AAPL for Apple Inc."
          }
        },
        "required": ["ticker"]
      }
    }
  ]

  And then asked the model "What's the S&P 500 at today?", the model might produce tool_use content blocks in the response like this:

  [
    {
      "type": "tool_use",
      "id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "name": "get_stock_price",
      "input": { "ticker": "^GSPC" }
    }
  ]

  You might then run your get_stock_price tool with {"ticker": "^GSPC"} as an input, and return the following back to the model in a subsequent user message:

  [
    {
      "type": "tool_result",
      "tool_use_id": "toolu_01D7FLrfh4GYq7yT1ULFeyMV",
      "content": "259.75 USD"
    }
  ]

  Tools can be used for workflows that include running client-side tools and functions, or more generally whenever you want the model to produce a particular JSON structure of output.

  See our guide for more details.

• tools

   final MessageCreateParams.Body.Builder tools(JsonField<List<ToolUnion>> tools)

  Sets Builder.tools to an arbitrary JSON value.

  You should usually call Builder.tools with a well-typed List<ToolUnion> value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• addTool

   final MessageCreateParams.Body.Builder addTool(ToolUnion tool)

  Adds a single ToolUnion to tools.

• addTool

   final MessageCreateParams.Body.Builder addTool(Tool tool)

  Alias for calling addTool with ToolUnion.ofTool(tool).

• addTool

   final MessageCreateParams.Body.Builder addTool(ToolBash20250124 bash20250124)

  Alias for calling addTool with ToolUnion.ofBash20250124(bash20250124).

• addTool

   final MessageCreateParams.Body.Builder addTool(CodeExecutionTool20250522 codeExecutionTool20250522)

  Alias for calling addTool with ToolUnion.ofCodeExecutionTool20250522(codeExecutionTool20250522).

• addTool

   final MessageCreateParams.Body.Builder addTool(CodeExecutionTool20250825 codeExecutionTool20250825)

  Alias for calling addTool with ToolUnion.ofCodeExecutionTool20250825(codeExecutionTool20250825).

• addTool

   final MessageCreateParams.Body.Builder addTool(CodeExecutionTool20260120 codeExecutionTool20260120)

  Alias for calling addTool with ToolUnion.ofCodeExecutionTool20260120(codeExecutionTool20260120).

• addTool

   final MessageCreateParams.Body.Builder addTool(MemoryTool20250818 memoryTool20250818)

  Alias for calling addTool with ToolUnion.ofMemoryTool20250818(memoryTool20250818).

• addTool

   final MessageCreateParams.Body.Builder addTool(ToolTextEditor20250124 textEditor20250124)

  Alias for calling addTool with ToolUnion.ofTextEditor20250124(textEditor20250124).

• addTool

   final MessageCreateParams.Body.Builder addTool(ToolTextEditor20250429 textEditor20250429)

  Alias for calling addTool with ToolUnion.ofTextEditor20250429(textEditor20250429).

• addTool

   final MessageCreateParams.Body.Builder addTool(ToolTextEditor20250728 textEditor20250728)

  Alias for calling addTool with ToolUnion.ofTextEditor20250728(textEditor20250728).

• addTool

   final MessageCreateParams.Body.Builder addTool(WebSearchTool20250305 webSearchTool20250305)

  Alias for calling addTool with ToolUnion.ofWebSearchTool20250305(webSearchTool20250305).

• addTool

   final MessageCreateParams.Body.Builder addTool(WebFetchTool20250910 webFetchTool20250910)

  Alias for calling addTool with ToolUnion.ofWebFetchTool20250910(webFetchTool20250910).

• addTool

   final MessageCreateParams.Body.Builder addTool(WebSearchTool20260209 webSearchTool20260209)

  Alias for calling addTool with ToolUnion.ofWebSearchTool20260209(webSearchTool20260209).

• addTool

   final MessageCreateParams.Body.Builder addTool(WebFetchTool20260209 webFetchTool20260209)

  Alias for calling addTool with ToolUnion.ofWebFetchTool20260209(webFetchTool20260209).

• addTool

   final MessageCreateParams.Body.Builder addTool(WebFetchTool20260309 webFetchTool20260309)

  Alias for calling addTool with ToolUnion.ofWebFetchTool20260309(webFetchTool20260309).

• addTool

   final MessageCreateParams.Body.Builder addTool(ToolSearchToolBm25_20251119 searchToolBm25_20251119)

  Alias for calling addTool with ToolUnion.ofSearchToolBm25_20251119(searchToolBm25_20251119).

• addTool

   final MessageCreateParams.Body.Builder addTool(ToolSearchToolRegex20251119 searchToolRegex20251119)

  Alias for calling addTool with ToolUnion.ofSearchToolRegex20251119(searchToolRegex20251119).

• topK

   final MessageCreateParams.Body.Builder topK(Long topK)

  Only sample from the top K options for each subsequent token.

  Used to remove "long tail" low probability responses. Learn more technical details here.

  Recommended for advanced use cases only. You usually only need to use temperature.

• topK

   final MessageCreateParams.Body.Builder topK(JsonField<Long> topK)

  Sets Builder.topK to an arbitrary JSON value.

  You should usually call Builder.topK with a well-typed Long value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• topP

   final MessageCreateParams.Body.Builder topP(Double topP)

  Use nucleus sampling.

  In nucleus sampling, we compute the cumulative distribution over all the options for each subsequent token in decreasing probability order and cut it off once it reaches a particular probability specified by top_p. You should either alter temperature or top_p, but not both.

  Recommended for advanced use cases only. You usually only need to use temperature.

• topP

   final MessageCreateParams.Body.Builder topP(JsonField<Double> topP)

  Sets Builder.topP to an arbitrary JSON value.

  You should usually call Builder.topP with a well-typed Double value instead. This method is primarily for setting the field to an undocumented or not yet supported value.

• additionalProperties

   final MessageCreateParams.Body.Builder additionalProperties(Map<String, JsonValue> additionalProperties)

• putAdditionalProperty

   final MessageCreateParams.Body.Builder putAdditionalProperty(String key, JsonValue value)

• putAllAdditionalProperties

   final MessageCreateParams.Body.Builder putAllAdditionalProperties(Map<String, JsonValue> additionalProperties)

• removeAdditionalProperty

   final MessageCreateParams.Body.Builder removeAdditionalProperty(String key)

• removeAllAdditionalProperties

   final MessageCreateParams.Body.Builder removeAllAdditionalProperties(Set<String> keys)

• build

   final MessageCreateParams.Body build()

  Returns an immutable instance of Body.

  Further updates to this Builder will not mutate the returned instance.

  The following fields are required:

  .maxTokens()
  .messages()
  .model()