OpenSea Introduces ERC-8257 Standard for Onchain AI Agent Tool Marketplace

NFT marketplace OpenSea is advancing ERC-8257, or the Agent Tool Registry, to address the fragmentation of AI agent tools across documentation, GitHub and closed directories, with no unified standards for discovery, authorization or payment. Developers can register individual APIs onchain and control access through NFTs, subscriptions or allowlists, enabling agents to obtain services autonomously.

OpenSea unveiled ERC-8257 on May 27, 2026. Its onchain registry and SDK already support Ethereum and Base, although the standard remains in draft form. In a demonstration, an NFT valuation tool costs $0.05 per request at the standard rate and $0.01 for holders of CHONK on Base. An agent can purchase an NFT, retry the request and gain access to the service.