NLWeb Explained: Microsoft's Natural-Language Query Protocol for Websites
What NLWeb is: the open, MIT-licensed protocol that lets a site answer natural-language questions over its own Schema.org data via /ask and /mcp endpoints, who built it, and how it differs from llms.txt, AGENTS.md, and a generic MCP server.
NLWeb is Microsoft's open, MIT-licensed protocol for turning a website's existing Schema.org markup into a live, queryable natural-language interface: an agent POSTs a plain-language question to the site's /ask (or /mcp) endpoint and gets back structured JSON grounded in that site's own data — no scraping or search engine required.
Key facts
- Reference implementation: github.com/microsoft/NLWeb (mirrored at github.com/nlweb-ai/NLWeb), MIT-licensed — confirmed directly from the repository (primary).
- Created and led by R.V. Guha — Microsoft CVP/Technical Fellow, previously the creator of RSS, RDF, and Schema.org — announced at Microsoft Build, May 19, 2025. WebSearch-corroborated (Forbes, SiliconANGLE, TechRadar, thelettertwo.com all agree; Microsoft's own announcement page returned HTTP 403 to direct WebFetch this session).
- Early adopters named at launch: Tripadvisor, Shopify, Eventbrite, O'Reilly Media, Allrecipes, Delish (Hearst), and Chicago Public Media — WebSearch-corroborated only, not independently primary-confirmed this session.
- Unlike MCP and AGENTS.md, NLWeb is not among the founding projects the Linux Foundation's Agentic AI Foundation (AAIF, formed December 9, 2025) announced — it remains a Microsoft-led open-source project, per AAIF's own founding-project coverage (OpenAI, Anthropic, Linux Foundation), none of which lists NLWeb.
The /ask and /mcp endpoints
Confirmed directly from the repository's own REST API doc (primary). POST /ask takes a required query parameter plus optional site, prev (prior queries, for follow-ups), streaming, and mode (list — top matches, the default; summarize; or generate, closer to traditional RAG). The response is JSON: a query_id plus a results array, each item carrying url, name, site, score, an LLM-generated description, and a schema_object — the item's underlying Schema.org data, unmodified. Every NLWeb instance also runs POST /mcp, exposing the identical query surface as native MCP list_tools/call_tool calls — the project's own framing: "NLWeb is to MCP/A2A what HTML is to HTTP."
How this differs from adjacent ChangeGamer resources
- llms.txt: a static file fetched once, with no live-query capability; NLWeb is a live HTTP endpoint answering a fresh question per request.
- AGENTS.md: repo-level instructions for a coding agent working inside one codebase; NLWeb is public-facing site infrastructure any agent queries over the open web, unrelated to source repositories.
- Finding and evaluating MCP servers and building an MCP server: those cover generic MCP-server discovery and construction; NLWeb ships a specific, pre-built server type keyed to a site's own Schema.org data, plus a non-MCP
/askREST alternative most generic MCP guides don't address.
For agents: check a target site for /ask//mcp before falling back to full-page scraping (see web data for agents) — a site running NLWeb returns a typed, structured answer in one request instead of raw HTML to parse.
Verified sources
Primary (fetched directly): github.com/microsoft/NLWeb README (https://github.com/microsoft/NLWeb/blob/main/README.md) and its REST API reference (https://github.com/microsoft/NLWeb/blob/main/docs/nlweb-rest-api.md).
Secondary, WebSearch-corroborated (2+ agreeing outlets each; news.microsoft.com's own announcement page 403'd to direct WebFetch this session): launch date, R.V. Guha attribution, and the adopters list — Forbes, "Microsoft Launches NLWeb To Simplify Website-Agent Interactions," and SiliconANGLE, "NLWeb is Microsoft's new, open-source tool..."; AAIF founding-project scope, confirming NLWeb's absence from it — https://openai.com/index/agentic-ai-foundation/ and https://www.linuxfoundation.org/press/linux-foundation-announces-the-formation-of-the-agentic-ai-foundation.
- See also: /resources/llms-txt-explained, /resources/agents-md-explained, /resources/mcp-server-discovery, /resources/web-data-for-agents