| Provider | Retrieved Sources Structure | Selected Citation Mechanism | URL Format & Offsets |
|---|---|---|---|
| Google (Gemini) | groundingChunks in grounding_metadata |
groundingSupports mapping text segments to chunk indices |
Redirect URIs resolved to target URLs with start/end character offsets |
| OpenAI (GPT) | action.sources / results in web_search_call |
url_citation annotations on output text |
Direct URLs matched via start_index and end_index |
| Anthropic (Claude) | web_search_tool_result content items |
citations list embedded in text content blocks |
Direct URLs with start_char_index and end_char_index offsets |
