Constructor Detail

Method Detail

• betas

   final MessageCountTokensParams.Builder betas(List<AnthropicBeta> betas)

  Optional header to specify the beta version(s) you want to use.

• betas

   final MessageCountTokensParams.Builder betas(Optional<List<AnthropicBeta>> betas)

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

• addBeta

   final MessageCountTokensParams.Builder addBeta(AnthropicBeta beta)

  Adds a single AnthropicBeta to betas.

• addBeta

   final MessageCountTokensParams.Builder addBeta(String value)

  Sets addBeta to an arbitrary String.

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

• body

   final MessageCountTokensParams.Builder body(MessageCountTokensParams.Body body)

  Sets the entire request body.

  This is generally only useful if you are already constructing the body separately. Otherwise, it's more convenient to use the top-level setters instead:

  • messages

  • model

  • cacheControl

  • contextManagement

  • mcpServers

  • etc.

• messages

   final MessageCountTokensParams.Builder messages(List<BetaMessageParam> 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 MessageCountTokensParams.Builder messages(JsonField<List<BetaMessageParam>> messages)

  Sets Builder.messages to an arbitrary JSON value.

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

• addMessage

   final MessageCountTokensParams.Builder addMessage(BetaMessageParam message)

  Adds a single BetaMessageParam to messages.

• addMessage

   final MessageCountTokensParams.Builder addMessage(BetaMessage message)

  Alias for calling addMessage with message.toParam().

• addUserMessage

   final MessageCountTokensParams.Builder addUserMessage(BetaMessageParam.Content content)

  Alias for calling addMessage with the following:

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

• addUserMessage

   final MessageCountTokensParams.Builder addUserMessage(String string)

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

• addUserMessageOfBetaContentBlockParams

   final MessageCountTokensParams.Builder addUserMessageOfBetaContentBlockParams(List<BetaContentBlockParam> betaContentBlockParams)

  Alias for calling addUserMessage with BetaMessageParam.Content.ofBetaContentBlockParams(betaContentBlockParams).

• addAssistantMessage

   final MessageCountTokensParams.Builder addAssistantMessage(BetaMessageParam.Content content)

  Alias for calling addMessage with the following:

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

• addAssistantMessage

   final MessageCountTokensParams.Builder addAssistantMessage(String string)

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

• addAssistantMessageOfBetaContentBlockParams

   final MessageCountTokensParams.Builder addAssistantMessageOfBetaContentBlockParams(List<BetaContentBlockParam> betaContentBlockParams)

  Alias for calling addAssistantMessage with BetaMessageParam.Content.ofBetaContentBlockParams(betaContentBlockParams).

• model

   final MessageCountTokensParams.Builder model(Model model)

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

• model

   final MessageCountTokensParams.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 MessageCountTokensParams.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 MessageCountTokensParams.Builder cacheControl(BetaCacheControlEphemeral cacheControl)

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

• cacheControl

   final MessageCountTokensParams.Builder cacheControl(Optional<BetaCacheControlEphemeral> cacheControl)

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

• cacheControl

   final MessageCountTokensParams.Builder cacheControl(JsonField<BetaCacheControlEphemeral> cacheControl)

  Sets Builder.cacheControl to an arbitrary JSON value.

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

• contextManagement

   final MessageCountTokensParams.Builder contextManagement(BetaContextManagementConfig contextManagement)

  Context management configuration.

  This allows you to control how Claude manages context across multiple requests, such as whether to clear function results or not.

• contextManagement

   final MessageCountTokensParams.Builder contextManagement(Optional<BetaContextManagementConfig> contextManagement)

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

• contextManagement

   final MessageCountTokensParams.Builder contextManagement(JsonField<BetaContextManagementConfig> contextManagement)

  Sets Builder.contextManagement to an arbitrary JSON value.

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

• mcpServers

   final MessageCountTokensParams.Builder mcpServers(List<BetaRequestMcpServerUrlDefinition> mcpServers)

  MCP servers to be utilized in this request

• mcpServers

   final MessageCountTokensParams.Builder mcpServers(JsonField<List<BetaRequestMcpServerUrlDefinition>> mcpServers)

  Sets Builder.mcpServers to an arbitrary JSON value.

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

• addMcpServer

   final MessageCountTokensParams.Builder addMcpServer(BetaRequestMcpServerUrlDefinition mcpServer)

  Adds a single BetaRequestMcpServerUrlDefinition to mcpServers.

• outputConfig

   final MessageCountTokensParams.Builder outputConfig(BetaOutputConfig outputConfig)

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

• outputConfig

   final MessageCountTokensParams.Builder outputConfig(JsonField<BetaOutputConfig> outputConfig)

  Sets Builder.outputConfig to an arbitrary JSON value.

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

• outputFormat

  @Deprecated(message = "deprecated") final MessageCountTokensParams.Builder outputFormat(BetaJsonOutputFormat outputFormat)

  Deprecated: Use output_config.format instead. See structured outputs

  A schema to specify Claude's output format in responses. This parameter will be removed in a future release.

• outputFormat

  @Deprecated(message = "deprecated") final MessageCountTokensParams.Builder outputFormat(Optional<BetaJsonOutputFormat> outputFormat)

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

• outputFormat

  @Deprecated(message = "deprecated") final MessageCountTokensParams.Builder outputFormat(JsonField<BetaJsonOutputFormat> outputFormat)

  Sets Builder.outputFormat to an arbitrary JSON value.

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

• speed

   final MessageCountTokensParams.Builder speed(MessageCountTokensParams.Speed speed)

  The inference speed mode for this request. "fast" enables high output-tokens-per-second inference.

• speed

   final MessageCountTokensParams.Builder speed(Optional<MessageCountTokensParams.Speed> speed)

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

• speed

   final MessageCountTokensParams.Builder speed(JsonField<MessageCountTokensParams.Speed> speed)

  Sets Builder.speed to an arbitrary JSON value.

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

• system

   final MessageCountTokensParams.Builder system(MessageCountTokensParams.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 MessageCountTokensParams.Builder system(JsonField<MessageCountTokensParams.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 MessageCountTokensParams.Builder system(String string)

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

• systemOfBetaTextBlockParams

   final MessageCountTokensParams.Builder systemOfBetaTextBlockParams(List<BetaTextBlockParam> betaTextBlockParams)

  Alias for calling system with System.ofBetaTextBlockParams(betaTextBlockParams).

• thinking

   final MessageCountTokensParams.Builder thinking(BetaThinkingConfigParam 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 MessageCountTokensParams.Builder thinking(JsonField<BetaThinkingConfigParam> thinking)

  Sets Builder.thinking to an arbitrary JSON value.

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

• thinking

   final MessageCountTokensParams.Builder thinking(BetaThinkingConfigEnabled enabled)

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

• thinking

   final MessageCountTokensParams.Builder thinking(BetaThinkingConfigDisabled disabled)

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

• thinking

   final MessageCountTokensParams.Builder thinking(BetaThinkingConfigAdaptive adaptive)

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

• enabledThinking

   final MessageCountTokensParams.Builder enabledThinking(Long budgetTokens)

  Alias for calling thinking with the following:

  BetaThinkingConfigEnabled.builder()
      .budgetTokens(budgetTokens)
      .build()

• toolChoice

   final MessageCountTokensParams.Builder toolChoice(BetaToolChoice 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 MessageCountTokensParams.Builder toolChoice(JsonField<BetaToolChoice> toolChoice)

  Sets Builder.toolChoice to an arbitrary JSON value.

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

• toolChoice

   final MessageCountTokensParams.Builder toolChoice(BetaToolChoiceAuto auto)

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

• toolChoice

   final MessageCountTokensParams.Builder toolChoice(BetaToolChoiceAny any)

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

• toolChoice

   final MessageCountTokensParams.Builder toolChoice(BetaToolChoiceTool tool)

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

• toolChoice

   final MessageCountTokensParams.Builder toolChoice(BetaToolChoiceNone none)

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

• toolToolChoice

   final MessageCountTokensParams.Builder toolToolChoice(String name)

  Alias for calling toolChoice with the following:

  BetaToolChoiceTool.builder()
      .name(name)
      .build()

• tools

   final MessageCountTokensParams.Builder tools(List<MessageCountTokensParams.Tool> 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 MessageCountTokensParams.Builder tools(JsonField<List<MessageCountTokensParams.Tool>> tools)

  Sets Builder.tools to an arbitrary JSON value.

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

• addTool

   final MessageCountTokensParams.Builder addTool(MessageCountTokensParams.Tool tool)

  Adds a single Tool to tools.

• addTool

   final MessageCountTokensParams.Builder addTool(BetaTool beta)

  Alias for calling addTool with Tool.ofBeta(beta).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolBash20241022 betaToolBash20241022)

  Alias for calling addTool with Tool.ofBetaToolBash20241022(betaToolBash20241022).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolBash20250124 betaToolBash20250124)

  Alias for calling addTool with Tool.ofBetaToolBash20250124(betaToolBash20250124).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaCodeExecutionTool20250522 betaCodeExecutionTool20250522)

  Alias for calling addTool with Tool.ofBetaCodeExecutionTool20250522(betaCodeExecutionTool20250522).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaCodeExecutionTool20250825 betaCodeExecutionTool20250825)

  Alias for calling addTool with Tool.ofBetaCodeExecutionTool20250825(betaCodeExecutionTool20250825).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaCodeExecutionTool20260120 betaCodeExecutionTool20260120)

  Alias for calling addTool with Tool.ofBetaCodeExecutionTool20260120(betaCodeExecutionTool20260120).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolComputerUse20241022 betaToolComputerUse20241022)

  Alias for calling addTool with Tool.ofBetaToolComputerUse20241022(betaToolComputerUse20241022).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaMemoryTool20250818 betaMemoryTool20250818)

  Alias for calling addTool with Tool.ofBetaMemoryTool20250818(betaMemoryTool20250818).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolComputerUse20250124 betaToolComputerUse20250124)

  Alias for calling addTool with Tool.ofBetaToolComputerUse20250124(betaToolComputerUse20250124).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolTextEditor20241022 betaToolTextEditor20241022)

  Alias for calling addTool with Tool.ofBetaToolTextEditor20241022(betaToolTextEditor20241022).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolComputerUse20251124 betaToolComputerUse20251124)

  Alias for calling addTool with Tool.ofBetaToolComputerUse20251124(betaToolComputerUse20251124).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolTextEditor20250124 betaToolTextEditor20250124)

  Alias for calling addTool with Tool.ofBetaToolTextEditor20250124(betaToolTextEditor20250124).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolTextEditor20250429 betaToolTextEditor20250429)

  Alias for calling addTool with Tool.ofBetaToolTextEditor20250429(betaToolTextEditor20250429).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolTextEditor20250728 betaToolTextEditor20250728)

  Alias for calling addTool with Tool.ofBetaToolTextEditor20250728(betaToolTextEditor20250728).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaWebSearchTool20250305 betaWebSearchTool20250305)

  Alias for calling addTool with Tool.ofBetaWebSearchTool20250305(betaWebSearchTool20250305).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaWebFetchTool20250910 betaWebFetchTool20250910)

  Alias for calling addTool with Tool.ofBetaWebFetchTool20250910(betaWebFetchTool20250910).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaWebSearchTool20260209 betaWebSearchTool20260209)

  Alias for calling addTool with Tool.ofBetaWebSearchTool20260209(betaWebSearchTool20260209).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaWebFetchTool20260209 betaWebFetchTool20260209)

  Alias for calling addTool with Tool.ofBetaWebFetchTool20260209(betaWebFetchTool20260209).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaWebFetchTool20260309 betaWebFetchTool20260309)

  Alias for calling addTool with Tool.ofBetaWebFetchTool20260309(betaWebFetchTool20260309).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolSearchToolBm25_20251119 betaToolSearchToolBm25_20251119)

  Alias for calling addTool with Tool.ofBetaToolSearchToolBm25_20251119(betaToolSearchToolBm25_20251119).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaToolSearchToolRegex20251119 betaToolSearchToolRegex20251119)

  Alias for calling addTool with Tool.ofBetaToolSearchToolRegex20251119(betaToolSearchToolRegex20251119).

• addTool

   final MessageCountTokensParams.Builder addTool(BetaMcpToolset betaMcpToolset)

  Alias for calling addTool with Tool.ofBetaMcpToolset(betaMcpToolset).

• additionalBodyProperties

   final MessageCountTokensParams.Builder additionalBodyProperties(Map<String, JsonValue> additionalBodyProperties)

• putAdditionalBodyProperty

   final MessageCountTokensParams.Builder putAdditionalBodyProperty(String key, JsonValue value)

• putAllAdditionalBodyProperties

   final MessageCountTokensParams.Builder putAllAdditionalBodyProperties(Map<String, JsonValue> additionalBodyProperties)

• removeAdditionalBodyProperty

   final MessageCountTokensParams.Builder removeAdditionalBodyProperty(String key)

• removeAllAdditionalBodyProperties

   final MessageCountTokensParams.Builder removeAllAdditionalBodyProperties(Set<String> keys)

• additionalHeaders

   final MessageCountTokensParams.Builder additionalHeaders(Headers additionalHeaders)

• additionalHeaders

   final MessageCountTokensParams.Builder additionalHeaders(Map<String, Iterable<String>> additionalHeaders)

• putAdditionalHeader

   final MessageCountTokensParams.Builder putAdditionalHeader(String name, String value)

• putAdditionalHeaders

   final MessageCountTokensParams.Builder putAdditionalHeaders(String name, Iterable<String> values)

• putAllAdditionalHeaders

   final MessageCountTokensParams.Builder putAllAdditionalHeaders(Headers additionalHeaders)

• putAllAdditionalHeaders

   final MessageCountTokensParams.Builder putAllAdditionalHeaders(Map<String, Iterable<String>> additionalHeaders)

• replaceAdditionalHeaders

   final MessageCountTokensParams.Builder replaceAdditionalHeaders(String name, String value)

• replaceAdditionalHeaders

   final MessageCountTokensParams.Builder replaceAdditionalHeaders(String name, Iterable<String> values)

• replaceAllAdditionalHeaders

   final MessageCountTokensParams.Builder replaceAllAdditionalHeaders(Headers additionalHeaders)

• replaceAllAdditionalHeaders

   final MessageCountTokensParams.Builder replaceAllAdditionalHeaders(Map<String, Iterable<String>> additionalHeaders)

• removeAdditionalHeaders

   final MessageCountTokensParams.Builder removeAdditionalHeaders(String name)

• removeAllAdditionalHeaders

   final MessageCountTokensParams.Builder removeAllAdditionalHeaders(Set<String> names)

• additionalQueryParams

   final MessageCountTokensParams.Builder additionalQueryParams(QueryParams additionalQueryParams)

• additionalQueryParams

   final MessageCountTokensParams.Builder additionalQueryParams(Map<String, Iterable<String>> additionalQueryParams)

• putAdditionalQueryParam

   final MessageCountTokensParams.Builder putAdditionalQueryParam(String key, String value)

• putAdditionalQueryParams

   final MessageCountTokensParams.Builder putAdditionalQueryParams(String key, Iterable<String> values)

• putAllAdditionalQueryParams

   final MessageCountTokensParams.Builder putAllAdditionalQueryParams(QueryParams additionalQueryParams)

• putAllAdditionalQueryParams

   final MessageCountTokensParams.Builder putAllAdditionalQueryParams(Map<String, Iterable<String>> additionalQueryParams)

• replaceAdditionalQueryParams

   final MessageCountTokensParams.Builder replaceAdditionalQueryParams(String key, String value)

• replaceAdditionalQueryParams

   final MessageCountTokensParams.Builder replaceAdditionalQueryParams(String key, Iterable<String> values)

• replaceAllAdditionalQueryParams

   final MessageCountTokensParams.Builder replaceAllAdditionalQueryParams(QueryParams additionalQueryParams)

• replaceAllAdditionalQueryParams

   final MessageCountTokensParams.Builder replaceAllAdditionalQueryParams(Map<String, Iterable<String>> additionalQueryParams)

• removeAdditionalQueryParams

   final MessageCountTokensParams.Builder removeAdditionalQueryParams(String key)

• removeAllAdditionalQueryParams

   final MessageCountTokensParams.Builder removeAllAdditionalQueryParams(Set<String> keys)

• build

   final MessageCountTokensParams build()

  Returns an immutable instance of MessageCountTokensParams.

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

  The following fields are required:

  .messages()
  .model()