One of the recurring friction points when using a coding agent on an existing codebase is that the agent starts with essentially no context about how the project actually works: what commands build it, what conventions the team follows, which directories are safe to modify freely versus which are generated or vendored, and what testing setup needs to run before a change is considered done. Historically this context either had to be re-explained in every session's prompt, baked into tool-specific configuration files that only worked with one particular agent, or left for the agent to infer by exploring the repository, which wastes time and produces inconsistent results. AGENTS.md addresses this with a deliberately simple idea: a single, plain-markdown file at the root of a repository that describes exactly this kind of setup and convention information in a format that isn't tied to any one vendor's tooling. What's notable about its traction, now used in more than sixty thousand projects and supported across most major agents including Cursor, Copilot, Devin, and Gemini CLI, is that it succeeded specifically by staying deliberately unopinionated and lightweight rather than trying to be a comprehensive specification format. For a team adopting agentic coding tools across multiple projects or multiple agent vendors, standardizing on a single AGENTS.md convention means writing that context once per repository rather than maintaining separate, tool-specific configuration for every agent the team happens to use. The effort required to add one is genuinely low, essentially just documenting things a new human contributor would also need to know, which makes it one of the highest-leverage, lowest-effort changes a team can make to get meaningfully better results out of whatever coding agents they're already using.