Pablo

On AI and Knowledge — Pablo Castro, Distinguished Engineer & CVP for AI Knowledge, Microsoft

Jul 17, 2026 · 17:35

Pablo Castro, Distinguished Engineer and CVP for AI Knowledge at Microsoft, argues that AI agents require three knowledge types—intrinsic (model training), extrinsic (RAG and grounding), and learned (optimization loops)—and demonstrates how Microsoft's Foundry IQ, Azure AI Search, and Agent Optimizer deliver them. He shows that combining retrieval methods outperforms individual ones, citing Azure AI Search evaluations where combined methods improve evidence recall and answer completeness. He introduces Foundry IQ as a layered system with agentic retrieval that reflects on data to satisfy information needs before returning results. Castro demonstrates creating a knowledge base that connects unstructured data, structured Parquet tables, and the web, then linking it to an agent via MCP server. He also showcases the Agent Optimizer, which uses hill climbing on baseline evaluations to automatically refine agent instructions, tool definitions, and skills based on runtime traces, enabling continuous learning loops that capture organizational differentiation.

RAG at scale: production ready GenAI apps with Azure AI Search

Feb 13, 2025 · 21:53

Pablo, a Distinguished Engineer at Microsoft, explains how Azure AI Search enables production-grade RAG applications at scale by addressing key scaling challenges: data volume, query load, workflow complexity, and diverse data types. He demonstrates the platform's hybrid retrieval combining vector search (HNSW, exhaustive), keyword search (BM25), and filters, with a two-stage system using cross-encoder re-ranking for improved quality, achieving 100ms re-ranking latency. Azure AI Search supports multi-billion vector indexes through 10–12x storage limit increases and quantization (int8, single-bit) preserving 90–95% precision, with oversampling for full-precision re-ranking. Integrated vectorization automates ingestion from Azure sources (blob, Cosmos DB, OneLake) with change tracking and format handling (PDFs, Office documents, images). OpenAI uses Azure AI Search to back ChatGPT file uploads and the Assistants API, scaling user limits 500x after Microsoft's infrastructure upgrades.