Claude Mythos 5.1

Anthropic — Claude Mythos 5.1

Model Details

Claude Mythos 5.1 is Anthropic's most capable model for cybersecurity defense and life sciences research, including threat intelligence, vulnerability discovery, red teaming, drug discovery, and biodefense screening.

Access is currently gated to a vetted set of organizations through Anthropic's trusted access programs, given the dual-use nature of these domains.

This model is a Preview and is made available to you as a "Beta Service" as defined in the AWS Service Terms. It is subject to your Agreement with AWS, the AWS Service Terms, and the applicable model EULA.

• Model launch date: September 1, 2026

• Model EOL date: N/A

• End User License Agreements and Terms of Use: View

• Model lifecycle: Active

• Context window: 1M tokens

• Max output tokens: 128K

• Sampling parameters: temperature must be 1.0 or unset; top_p must be 0.99 or unset; temperature and top_p cannot be specified together; top_k is not supported

• Reasoning: Supported (adaptive thinking is always on and cannot be disabled; effort level configurable — low, medium, high, xhigh, max; default: high)

• Knowledge cutoff: June 2026

• Marketplace product ID: prod-k24dbcuykobku

Input Modalities	Output Modalities
Audio	Embedding
Image	Image
Speech	Speech
Text	Text
Video	Video

Endpoints and APIs supported

The following tables show which endpoints and APIs are supported for Claude Mythos 5.1. For more information, see APIs supported by Amazon Bedrock and Endpoints supported by Amazon Bedrock.

Endpoint support

Endpoint	Supported
bedrock-runtime

APIs supported on bedrock-runtime endpoint

Messages	Responses	Chat Completions	Converse	Invoke

Tip

Whenever possible, we recommend using the bedrock-runtime endpoint for new applications. See Endpoints supported by Amazon Bedrock for details.

Capabilities and Features

Bedrock Features

Features supported using bedrock-runtime endpoint

Supported	Not Supported
Response streaming Prompt caching Abuse detection Guardrails Prompt optimization Knowledge base Model evaluation Prompt management Flows Agents	Intelligent prompt routing

Prompt caching using bedrock-runtime endpoint

For more information, see Prompt caching for faster model inference.

Prompt caching supported	Min tokens per cache checkpoint	Max cache checkpoints per request	Supported TTL	Fields that accept prompt cache checkpoint
Yes	512	4	5 minutes, 1 hour	system, messages, and tools

Pricing

For pricing information, see the Amazon Bedrock Pricing page.

Programmatic Access

Use the following model IDs and endpoint URLs to access this model programmatically. For more information about the available APIs and endpoints, see APIs supported and Endpoints supported.

Endpoint	Model ID	In-Region endpoint URL	Geo inference ID	Global inference ID
bedrock-runtime	anthropic.claude-mythos-5-1	N/A	us.anthropic.claude-mythos-5-1	global.anthropic.claude-mythos-5-1

For example, if region is us-east-1 (N. Virginia), then the bedrock-runtime endpoint URL will be "https://bedrock-runtime.us-east-1.amazonaws.com".

Service Tiers

Amazon Bedrock offers multiple service tiers to match your workload requirements. Standard provides pay-per-token access with no commitment (set "service_tier": "default" or omit the field). Priority delivers the fastest response times for a price premium (set "service_tier": "priority"). Flex provides lower-cost access for flexible, non-time-sensitive workloads (set "service_tier": "flex"). Reserved provides dedicated throughput with a term commitment for predictable workloads; it is set at the account level rather than per request (contact your AWS account team to enable). For more information, see service tiers.

Standard	Priority	Flex	Reserved

Regional Availability

Regional availability at a glance

Amazon Bedrock offers three inference options: In-Region keeps requests within a single Region for strict compliance, Geo Cross-Region routes across Regions within a geography (such as US, EU, and APAC) while respecting data residency, and Global Cross-Region routes anywhere worldwide when there are no residency constraints. Refer to the Regional availability by models page for more details.

Region	In-Region	Geo	Global
us-east-1 (N. Virginia)
us-east-2 (Ohio)
us-west-1 (N. California)
us-west-2 (Oregon)
ca-central-1 (Canada)
ca-west-1 (Calgary)
eu-central-1 (Frankfurt)
eu-central-2 (Zurich)
eu-north-1 (Stockholm)
eu-south-1 (Milan)
eu-south-2 (Spain)
eu-west-1 (Ireland)
eu-west-2 (London)
eu-west-3 (Paris)
ap-east-2 (Taipei)
ap-northeast-1 (Tokyo)
ap-northeast-2 (Seoul)
ap-northeast-3 (Osaka)
ap-south-1 (Mumbai)
ap-south-2 (Hyderabad)
ap-southeast-1 (Singapore)
ap-southeast-2 (Sydney)
ap-southeast-3 (Jakarta)
ap-southeast-4 (Melbourne)
ap-southeast-5 (Malaysia)
ap-southeast-6 (New Zealand)
ap-southeast-7 (Thailand)
il-central-1 (Tel Aviv)
me-central-1 (UAE)
me-south-1 (Bahrain)
af-south-1 (Cape Town)
sa-east-1 (São Paulo)
mx-central-1 (Mexico)

Data Retention

To use this model, you must opt in to provider data sharing by setting your data retention mode to provider_data_share. You can configure this in the Amazon Bedrock console or via the Data Retention API. For more information, see Amazon Bedrock abuse detection.

Quotas and Limits

Your AWS account has default quotas to maintain the performance of the service and to ensure appropriate usage of Amazon Bedrock. The default quotas assigned to an account might be updated depending on regional factors, payment history, fraudulent usage, and/or approval of a quota increase request. For more information, see Quotas for Amazon Bedrock documentation and see the limits for the model.

Sample Code

Step 1 - AWS Account: If you have an AWS account already, skip this step. If you are new to AWS, sign up for an AWS account.

Step 2 - API key: Go to the Amazon Bedrock console and generate a long-term API key.

Step 3 - Get the SDK: To use this getting started guide, you must have Python already installed. Then install the relevant software depending on the APIs you are using.

Messages API

pip install -U anthropic aws-bedrock-token-generator

Invoke/Converse API

pip install boto3

Step 4 - Set environment variables: Configure your environment to use the API key for authentication.

Messages API

AWS_BEARER_TOKEN_BEDROCK="<provide your Bedrock API key>"

Invoke/Converse API

AWS_BEARER_TOKEN_BEDROCK="<provide your Bedrock API key>"

Step 5 - Run your first inference request: Save the file as bedrock-first-request.py

Messages API

from anthropic import Anthropic
from aws_bedrock_token_generator import provide_token

token = provide_token(region="us-east-1")

client = Anthropic(
    base_url="https://bedrock-runtime.us-east-1.amazonaws.com/anthropic",
    api_key=token,
)

response = client.messages.create(
    model="global.anthropic.claude-mythos-5-1",
    max_tokens=1024,
    messages=[{"role": "user", "content": "Can you explain the features of Amazon Bedrock?"}],
)

print(response)

Invoke API

import json
import boto3

client = boto3.client('bedrock-runtime', region_name='us-east-1')
response = client.invoke_model(
    modelId='global.anthropic.claude-mythos-5-1',
    body=json.dumps({
            'anthropic_version': 'bedrock-2023-05-31',
            'messages': [{ 'role': 'user', 'content': 'Can you explain the features of Amazon Bedrock?'}],
            'max_tokens': 1024
    })
)
print(json.loads(response['body'].read()))

Converse API

import boto3

client = boto3.client('bedrock-runtime', region_name='us-east-1')
response = client.converse(
    modelId='global.anthropic.claude-mythos-5-1',
    messages=[
        {
            'role': 'user',
            'content': [{'text': 'Can you explain the features of Amazon Bedrock?'}]
        }
    ]
)
print(response)