To integrate Claude LLM into a Voiceflow assistant, first sign up for early access and gain access to the Anthropic Developer Console, then generate an API key. From there, follow steps to create an integration by logging in to your Voiceflow account, choosing the project, reaching for the API step, entering the API endpoint URL, setting the API method and headers, including the API key, and providing the required JSON payload. You can test the assistant while prototyping but note that commercial deployment requires a services agreement with Anthropic and evaluation API keys are provided under non-commercial terms.