Five vendors agreed on a plugin format. Read what they agreed not to standardise.
Agent Plugins 1.0.0 published yesterday: a vendor-neutral package format for the things people already write for coding agents. A plugin is a directory — plugin.json names it, skills/ holds Agent Skills, mcp.json describes MCP servers, and reverse-domain folders let a client add its own behaviour without touching the portable core.1 The technical steering committee is Amazon, Cursor, Microsoft, OpenAI and Vercel. It is not a press release with a roadmap: Codex shipped support the same day, and you can install portable plugins and search local, personal, workspace and remote catalogues from the CLI today.2
The specification draws the line itself. Portability covers the layout; distribution, installation, permissions and user experience stay under each client's control.1 So a plugin written once still lands in a different installer, a different trust model and a different approval flow in every tool that reads it. That is a real floor, and it is a floor deliberately laid below the parts that actually hurt.
the format is one day old and one client ships it. If you maintain plugins for two agents, read the spec now — the directory shape is cheap to adopt and costs nothing if it wins. Do not rewrite your distribution around it yet.
Deeper — the objection, and why it is not noise
- Mario Zechner, who maintains a competing harness, read the specification and posted: "after reading the spec, this actually solves nothing... just like with the skills 'standard', which to date nobody has implemented properly, because for that you basically have to reverse Claude Code's slop."8 Both sides are describing the same document. The disagreement is about whether an interoperability floor that excludes installation and permissions deserves the word standard.
- Governance is public — proposals go through GitHub Discussions and are expected to establish a portability need plus implementer support before landing.1 That is the part most vendor consortia skip, and it is the reason to take this more seriously than the last format announcement.
- The practical test is the second client that can install a plugin written for the first without editing it. Nobody has demonstrated that yet.