The bottleneck isn't "how do I define my agent." It's "how do agents find the right tool for their task."

I run a search service that 110+ agents use. They don't browse catalogs or read specs. They describe what they need ("MCP server for Postgres") and expect results back immediately. The definition format matters far less than whether the description is good and whether something can find it.

SKILL.md, AGENTS.md, SOUL.md, they're all converging on the same idea. That's fine. But the portability win only kicks in once there's a discovery layer that can index all of them. Without that, these files are just README.md with a new name.