Reference Specification: /.well-known/ai.txt, /ai/summary.json & /.well-known/mcp.json
Updated 2026-11-14 · Live reference endpoints on this host: /.well-known/ai.txt · /ai/summary.json · /.well-known/mcp.json

In our HTTP/HTML readiness check of 2459 B2B SaaS domains, 64.3% already ship basic /llms.txt (often auto-generated by docs hosts), yet 99.8% return 404 on /ai/summary.json and over 98% lack /.well-known/ai.txt and /.well-known/mcp.json. These figures measure public HTTP responses and HTML metadata rather than answers from ChatGPT, Gemini, Perplexity, or Claude.

1. /ai/summary.json — Deterministic Entity & Commercial Fact Sheet

{
  "schema_version": "1.0",
  "entity": "Acme Cloud",
  "domain": "acme.dev",
  "category": "Developer Infrastructure",
  "pricing_url": "https://acme.dev/pricing.md",
  "starting_price_usd": 49,
  "compliance": ["SOC 2 Type II", "GDPR"],
  "primary_alternatives": ["IncumbentA", "IncumbentB"],
  "updated_at": "2026-11-14"
}

2. /.well-known/ai.txt & /.well-known/mcp.json — Crawler Policy & Agent Tools

# /.well-known/ai.txt
User-Agent: *
Allow-AI-Search: true
LLMs-Txt: https://acme.dev/llms.txt
LLMs-Full: https://acme.dev/llms-full.txt
Pricing-Markdown: https://acme.dev/pricing.md
Entity-Summary: https://acme.dev/ai/summary.json
MCP-Descriptor: https://acme.dev/.well-known/mcp.json