# Request and Response
The request body is passed in the `body` field of a request to [InvokeModel](https://docs.aws.amazon.com/bedrock/latest/APIReference/API_runtime_InvokeModel.html) or [InvokeModelWithResponseStream](https://docs.aws.amazon.com/bedrock/latest/APIReference/API_runtime_InvokeModelWithResponseStream.html).
**Note**
Restrictions apply to the following operations: `InvokeModel`, `InvokeModelWithResponseStream`, `Converse`, and `ConverseStream`. See [API restrictions](inference-api-restrictions.md) for details.
**Warning**
Claude Sonnet 4.5 and Claude Haiku 4.5 support specifying either the `temperature` or `top_p` parameter, but not both. This does not apply to any older models.
------
#### [ Request ]
Anthropic Claude has the following inference parameters for a messages inference call.
```
{
"anthropic_version": "bedrock-2023-05-31",
"anthropic_beta": ["computer-use-2024-10-22"]
"max_tokens": int,
"system": string,
"messages": [
{
"role": string,
"content": [
{ "type": "image", "source": { "type": "base64", "media_type": "image/jpeg", "data": "content image bytes" } },
{ "type": "text", "text": "content text" }
]
}
],
"temperature": float,
"top_p": float,
"top_k": int,
"tools": [
{
"type": "custom",
"name": string,
"description": string,
"input_schema": json
},
{
"type": "computer_20241022",
"name": "computer",
"display_height_px": int,
"display_width_px": int,
"display_number": 0 int
},
{
"type": "bash_20241022",
"name": "bash"
},
{
"type": "text_editor_20241022",
"name": "str_replace_editor"
}
],
"tool_choice": {
"type" : string,
"name" : string,
},
"stop_sequences": [string]
}
```
The following are required parameters.
+ **anthropic\$1version** – (Required) The anthropic version. The value must be `bedrock-2023-05-31`.
+ **max\$1tokens** – (Required) The maximum number of tokens to generate before stopping.
Note that Anthropic Claude models might stop generating tokens before reaching the value of `max_tokens`. Different Anthropic Claude models have different maximum values for this parameter. For more information, see [Model comparison](https://docs.anthropic.com/claude/docs/models-overview#model-comparison).
+ **messages** – (Required) The input messages.
+ **role** – The role of the conversation turn. Valid values are `user` and `assistant`.
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html)
+ **content** – (required) The content of the conversation turn, as an array of objects. Each object contains a **type** field, in which you can specify one of the following values:
+ `text` – If you specify this type, you must include a **text** field and specify the text prompt as its value. If another object in the array is an image, this text prompt applies to the images.
+ `image` – If you specify this type, you must include a **source** field that maps to an object with the following fields:
+ **type** – (required) The encoding type for the image. You can specify `base64`.
+ **media\$1type** – (required) The type of the image. You can specify the following image formats.
+ `image/jpeg`
+ `image/png`
+ `image/webp`
+ `image/gif`
+ **data** – (required) The base64 encoded image bytes for the image. The maximum image size is 3.75MB. The maximum height and width of an image is 8000 pixels.
The following are optional parameters.
+ **system** – (Optional) The system prompt for the request.
A system prompt is a way of providing context and instructions to Anthropic Claude, such as specifying a particular goal or role. For more information, see [System prompts](https://docs.anthropic.com/en/docs/system-prompts) in the Anthropic documentation.
**Note**
You can use system prompts with Anthropic Claude version 2.1 or higher.
+ **anthropic\$1beta** – (Optional) The anthropic beta parameter is a list of strings of beta headers used to indicate opt-in to a particular set of beta features.
**Note**
The 1 million token context length variant of Claude Sonnet 4 is available to you in select AWS Regions as a "Beta Service" as defined in the AWS Service Terms. It is subject to your Agreement with AWS and the AWS Service Terms, and the applicable model EULA. Please see the [Amazon Bedrock Pricing](https://aws.amazon.com/bedrock/pricing/) page for more information about the pricing for longer context requests. Separate service quotas apply (for more information, see **Service Quotas** in the AWS Management Console).
Available beta headers include the following:
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html)
+ **stop\$1sequences** – (Optional) Custom text sequences that cause the model to stop generating. Anthropic Claude models normally stop when they have naturally completed their turn, in this case the value of the `stop_reason` response field is `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 text strings, the value of the `stop_reason` response field is `stop_sequence` and the value of `stop_sequence` contains the matched stop sequence.
The maximum number of entries is 8191.
+ **temperature** – (Optional) The amount of randomness injected into the response.
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html)
+ **top\$1p** – (Optional) Use nucleus sampling.
In nucleus sampling, Anthropic Claude computes the cumulative distribution over all the options for each subsequent token in decreasing probability order and cuts it off once it reaches a particular probability specified by `top_p`. When adjusting sampling parameters, modify either `temperature` or `top_p`. Do not modify both at the same time.
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html)
+ **top\$1k** – (Optional) Only sample from the top K options for each subsequent token.
Use `top_k` to remove long tail low probability responses.
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html)
+ **tools** – (Optional) Definitions of tools that the model may use.
**Note**
Requires an Anthropic Claude 3 model.
If you include `tools` in your 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.
You can pass the following tool types:
**Custom**
Definition for a custom tool.
+ (optional) **type** – The type of the tool. If defined, use the value `custom`.
+ **name** – The name of the tool.
+ **description** – (optional, but strongly recommended) The description of the tool.
+ **input\$1schema** – The JSON schema for the tool.
**Computer**
Definition for the computer tool that you use with the computer use API.
+ **type** – The value must be `computer_20241022`.
+ **name** – The value must be `computer`.
+ (Required) **display\$1height\$1px** – The height of the display being controlled by the model, in pixels..
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html)
+ (Required) **display\$1width\$1px** – The width of the display being controlled by the model, in pixels.
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html)
+ (Optional) **display\$1number** – The display number to control (only relevant for X11 environments). If specified, the tool will be provided a display number in the tool definition.
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/bedrock/latest/userguide/model-parameters-anthropic-claude-messages-request-response.html)
**bash**
Definition for the bash tool that you use with the computer use API.
+ (optional) **type** – The value must be `bash_20241022`.
+ **name** – The value must be `bash`. the tool.
**text editor**
Definition for the text editor tool that you use with the computer use API.
+ (optional) **type** – The value must be `text_editor_20241022`.
+ **name** – The value must be `str_replace_editor`. the tool.
+ **tool\$1choice** – (Optional) Specifices how the model should use the provided tools. The model can use a specific tool, any available tool, or decide by itself.
**Note**
Requires an Anthropic Claude 3 model.
+ **type** – The type of tool choice. Possible values are `any` (use any available tool), `auto` (the model decides), and `tool` (use the specified tool).
+ **name** – (Optional) The name of the tool to use. Required if you specify `tool` in the `type` field.
------
#### [ Response ]
The Anthropic Claude model returns the following fields for a messages inference call.
```
{
"id": string,
"model": string,
"type" : "message",
"role" : "assistant",
"content": [
{
"type": string,
"text": string,
"image" :json,
"id": string,
"name":string,
"input": json
}
],
"stop_reason": string,
"stop_sequence": string,
"usage": {
"input_tokens": integer,
"output_tokens": integer
}
}
```
Example responses with new stop\$1reason values:
```
// Example with refusal
{
"stop_reason": "refusal",
"content": [
{
"type": "text",
"text": "I can't help with that request."
}
]
}
// Example with tool_use
{
"stop_reason": "tool_use",
"content": [
{
"type": "tool_use",
"id": "toolu_123",
"name": "calculator",
"input": {"expression": "2+2"}
}
]
}
// Example with model_context_window_exceeded (Claude Sonnet 4.5)
{
"stop_reason": "model_context_window_exceeded",
"content": [
{
"type": "text",
"text": "The response was truncated due to context window limits..."
}
]
}
```
+ **id** – The unique identifier for the response. The format and length of the ID might change over time.
+ **model** – The ID for the Anthropic Claude model that made the request.
+ **stop\$1reason** – The reason why Anthropic Claude stopped generating the response.
+ **end\$1turn** – The model reached a natural stopping point
+ **max\$1tokens** – The generated text exceeded the value of the `max_tokens` input field or exceeded the maximum number of tokens that the model supports.' .
+ **stop\$1sequence** – The model generated one of the stop sequences that you specified in the `stop_sequences` input field.
+ **refusal** – Claude refuses to generate a response due to safety concerns
+ **tool\$1use** – Claude is calling a tool and expects you to execute it
+ **model\$1context\$1window\$1exceeded** – the model stopped generation due to hitting the context window limit.
+ New with Claude Sonnet 4.5
+ **stop\$1sequence** – The stop sequence that ended the generation.
+ **type** – The type of response. The value is always `message`.
+ **role** – The conversational role of the generated message. The value is always `assistant`.
+ **content** – The content generated by the model. Returned as an array. There are three types of content, *text*, *tool\$1use* and *image*.
+ *text* – A text response.
+ **type** – The type of the content. This value is `text`.
+ **text** – If the value of `type` is text, contains the text of the content.
+ *tool use* – A request from the model to use a tool.
+ **type** – The type of the content. This value is `tool_use`.
+ **id** – The ID for the tool that the model is requesting use of.
+ **name** – Contains the name of the requested tool.
+ **input** – The input parameters to pass to the tool.
+ *Image* – A request from the model to use a tool.
+ **type** – The type of the content. This value is `image`.
+ **source** – Contains the image. For more information, see [Multimodal prompts](model-parameters-anthropic-claude-messages.md#model-parameters-anthropic-claude-messages-multimodal-prompts).
+ **usage** – Container for the number of tokens that you supplied in the request and the number tokens of that the model generated in the response.
+ **input\$1tokens** – The number of input tokens in the request.
+ **output\$1tokens** – The number tokens of that the model generated in the response.
+ **stop\$1sequence** – The model generated one of the stop sequences that you specified in the `stop_sequences` input field.
------
## Effort parameter (beta)
The `effort` parameter is an alternative to thinking token budgets for Claude Opus 4.5. This parameter tells Claude how liberally it should spend tokens to produce the best result, adjusting token usage across thinking, tool calls, and user communication. It can be used with or without extended thinking mode.
The effort parameter can be set to:
+ `high` (default) – Claude spends as many tokens as needed for the best result
+ `medium` – Balanced token usage
+ `low` – Conservative token usage
To use this feature you must pass the beta header `effort-2025-11-24`.
Request example:
```
{
"anthropic_version": "bedrock-2023-05-31",
"anthropic_beta": [
"effort-2025-11-24"
],
"max_tokens": 4096,
"output_config": {
"effort": "medium"
},
"messages": [{
"role": "user",
"content": "Analyze this complex dataset and provide insights"
}]
}
```