Using Claude Mythos 5 on GCP Vertex AI

Quick Start

1. 1
   Create an account at GCP Vertex AI and generate an API key.
2. 2
   Use the GCP Vertex AI SDK or REST API to call claude-mythos-5 — see the documentation for request format.

Code Examples

import os
import vertexai
from vertexai.generative_models import GenerativeModel

# Reads GOOGLE_CLOUD_PROJECT from env; authenticates via Application Default Credentials
vertexai.init(project=os.environ["GOOGLE_CLOUD_PROJECT"], location="us-central1")
model = GenerativeModel("claude-mythos-5")
response = model.generate_content("Hello")
print(response.text)

About GCP Vertex AI

Google Cloud Vertex AI is a comprehensive machine learning platform that provides end-to-end solutions for developing, deploying, and managing AI models. The platform offers a unified interface that integrates various tools and services, enabling users to efficiently handle the entire machine learning lifecycle. Key features include AutoML capabilities for building custom models with minimal coding, a managed notebook environment for prototyping, and robust MLOps tools for model monitoring and versioning. Vertex AI supports both pre-trained models and custom training, making it versatile for a wide range of applications such as natural language processing, image recognition, and predictive analytics. The platform's design focuses on increasing productivity and accelerating time-to-market for AI solutions. By consolidating multiple AI tools into a single ecosystem, Vertex AI reduces manual effort and enhances collaboration among data scientists and engineers. Its scalable architecture allows organizations to efficiently manage large datasets and complex models, while the pay-as-you-go pricing model makes it accessible for businesses of all sizes. Additionally, Vertex AI's integration with popular open-source frameworks like TensorFlow and PyTorch enables users to leverage existing models and tools, fostering innovation and facilitating the development of customized AI applications tailored to specific business needs.

Vertex AI is Google Cloud's managed AI platform, offering access to Gemini models and hundreds of partner models alongside tools for fine-tuning, grounding, vector search, and end-to-end MLOps pipelines.

Pricing on GCP Vertex AI

Capabilities

About Claude Mythos 5

Anthropic's access-gated frontier model for approved Project Glasswing cybersecurity defenders and biomedical research organizations. Shares the same underlying architecture as Claude Fable 5 but operates with safety classifiers lifted in specific domains: cybersecurity safeguards are removed for all Glasswing participants, while biology safeguards are additionally removed for approved biology-track participants. Succeeds Claude Mythos Preview with significantly reduced pricing ($10/$50 per MTok input/output vs. $25/$125 for Mythos Preview), a 1M-token context window, 128k max output tokens, adaptive thinking always on (raw chain of thought never returned), vision, tool use, structured outputs, and the effort parameter for controlling thinking depth. Extended thinking with manual budget_tokens is not supported. Anthropic disabled Mythos 5 access for all customers on June 12, 2026 after the same US export control directive affecting Claude Fable 5 and says it is working to restore access.