OpenA2A This document defines ai-safety.txt, a plain-text declaration format that a domain publishes at a well-known location to communicate its AI-safety posture to autonomous agents and agent-driven browsers. Modeled on the robots.txt convention, an ai-safety.txt file lets a domain assert, in a machine-readable form, whether its content is authored by the domain rather than user-generated, whether that content is hardened against prompt injection, and whether it is rendered consistently to human and agent user agents. The file also carries a security contact, a link to an external verification record, and the date the declaration was last verified. The declarations in an ai-safety.txt file are self-asserted by the publishing domain. This document specifies the file format and its well-known location, and it is explicit that a consuming agent treats a declaration as a hint rather than as proof, verifying it against independent evidence where such evidence is available.