Anthropic FAQ & Answers

The Anthropic SDK provides a beta token counting API via client.beta.messages.count_tokens() method. In Python, use: client.beta.messages.count_tokens(betas=['token-counting-2024-11-01'], model='claude-3-5-sonnet-20241022', messages=[...], system='...'). In TypeScript/JavaScript, use: await client.messages.countTokens({model: 'claude-3-5-sonnet-20240620', messages: [...]}). The method accepts the same parameters as the Messages API including system prompts, messages, tools, images, and PDFs. It returns the exact input token count that matches billing. The beta flag 'token-counting-2024-11-01' is required for Python SDK. For PDFs, add the beta flag 'pdfs-2024-09-25'. The API endpoint is https://api.anthropic.com/v1/messages/count_tokens with headers x-api-key, anthropic-version: 2023-06-01, and content-type: application/json.