Understanding Agentic Resource Discovery (ARD): The Emerging Web Standard
An in-depth look at the multi-stakeholder initiative backed by Google, Microsoft, and Hugging Face to standardize how AI agents discover capabilities at runtime.
The Dynamic Discovery Problem
Today's AI agents are heavily limited by hard-coded tool integrations. If an agent needs to calculate compound interest or format a spreadsheet, the developer must pre-register and hard-code those tools in the agent's context window. But as the ecosystem grows to millions of specialized tools, hard-coding becomes impossible. We need a way for agents to discover capabilities dynamically at runtime.
Enter the ARD Specification
Agentic Resource Discovery (ARD) is an emerging open web specification designed to establish a federated, discoverable network of AI capabilities. Backed by industry leaders including Google, Microsoft, Hugging Face, GoDaddy, and Snowflake, the protocol defines a machine-readable directory format that websites publish directly on their own domains.
The "ai-catalog.json" Manifest
At the heart of the ARD protocol is the "ai-catalog.json" manifest file, served at the canonical location https://yourdomain.com/.well-known/ai-catalog.json. This file acts as the "homepage for agents", declaring available APIs, capabilities, and MCP servers along with representative queries. Crawler registries index these endpoints semantically, making them instantly searchable for AI clients.
Securing Identity with did:web
Because agents are executing real actions on behalf of users, verification is critical. Rather than relying on centralized directories, ARD uses domain-level trust. By binding catalogs cryptographically with decentralized identifiers (did:web), agents can verify that a tool truly belongs to the host organization, ensuring execution safety.
Why the Future of the Web is Agent-Readable
As agentic workflows scale, businesses that publish standardized catalogs will see their APIs discovered and called automatically by AI clients, driving a new wave of B2B integration. ARD is laying the foundation for a fully autonomous, semantic web.