Recently, Anthropic has introduced a new feature named "Citations," which aims to link AI-generated responses to specific sentences and paragraphs within original documents. Through Anthropic's API and Google Cloud's Vertex AI platform, developers can directly use documents provided by users, such as emails or PDF files, as references for AI responses.

The core of the Citations feature is its ability to connect AI-generated outputs with specific content from source documents. This change simplifies the development workflow, reducing reliance on complex prompt engineering. Internal evaluations show that compared to custom implementations, the Citations feature can increase recall accuracy by up to 15%. Currently, this feature supports the Claude 3.5, Sonnet, and Haiku models and is available on both Anthropic's API and Vertex AI.

In the past, developers often had to design detailed prompts to embed citation information in AI outputs. However, this method frequently led to inconsistent results and required high levels of prompt engineering. The introduction of the Citations feature allows developers to attach source documents directly to the API context window, enabling Claude models to automatically reference relevant sentences and paragraphs from these source documents in their replies, thereby reducing the risk of misinformation and improving traceability.

Specifically, the Citations feature can be applied in various scenarios: summarizing long documents and linking each summary point back to its original source; providing detailed query answers for complex documents like legal case files or financial reports; and creating customer support systems that cite exact sources from product manuals and FAQs.

When processing documents, the Citations feature breaks them down into sentence-level "chunks" and passes them along with user queries to the AI. This ensures that the AI's responses can cite specific content and format it to reference document pages, text ranges, or custom content blocks. While this may slightly increase input token costs, the cited text does not count towards output tokens, offering cost-effectiveness for developers.

In practical applications, several organizations have already adopted the Citations feature. For example, Thomson Reuters integrated it into its CoCounsel AI platform to enhance trust and reduce misinformation risks in legal and tax advisory services. Another financial AI provider, Endex, reported a 20% improvement in citation accuracy after using the Citations feature, eliminating citation format errors and streamlining multi-stage financial research processes.

Overall, the launch of the Citations feature is expected to strengthen the appeal of Claude models among developers seeking robust, traceable AI integration. Its design also complements other API features, such as token counting and batch processing, providing a seamless experience across multiple application scenarios.