Six AI Giants Agree on a 'Universal Plugin' Standard: Build Once, Run Everywhere—But Anthropic, the Inventor of the Format, Isn't on the List (Latest as of 2026-08)

If you’ve used more than one AI assistant, you’ve probably hit this snag: a small tool or skill you set up in Tool A has to be rebuilt from scratch when you switch to Tool B.

On 2026-08-06, five companies that normally compete with each other—OpenAI, AWS, Microsoft, Cursor (parent company Anysphere), and Vercel—jointly announced Agent Plugins 1.0, which in plain terms is “a unified packaging spec for AI plugins.” On 8/12, GitHub announced full-line support in Copilot, including the US$0 free tier.

But after going page by page through the spec document, all six companies’ official sites, and Claude Code’s official docs, I found something few people are talking about: the two things this standard packages (Skills and MCP) were both invented by Anthropic, and Anthropic is not on the list. Here’s everything I found.

1. What happened, in 30 seconds

• 2026-08-06: Agent Plugins 1.0.0 spec published. Vercel’s official blog states it originated as their own proposal, then was jointly revised by AWS, Anysphere, GitHub, Microsoft, OpenAI, and Vercel; the initial technical steering committee (Core Maintainers) is made up of AWS, Cursor, Microsoft, OpenAI, and Vercel.
• Same day: Google’s official developer blog announced it was joining as a Core Maintainer, represented by Kevin Hou, and that support would be built into its own Agents CLI and Data Agent Kit.
• Clients supported on launch day (per Vercel’s official text): ChatGPT and Codex, Cursor, GitHub Copilot, Kiro, VS Code.
• 2026-08-12: GitHub’s official changelog states “Support is generally available in VS Code, Copilot CLI, the GitHub Copilot SDK, and the GitHub Copilot app, on all Copilot plans"—explicitly stated in black and white as “all plans.”

(Dates verified: 2026-08-14, sources at the end of the article)

2. What problem does this actually solve? A plug analogy

MCP’s own official documentation uses the best analogy: “Think of MCP like a USB-C port for AI applications.”

So what is Agent Plugins? It’s not a new plug—it’s a unified spec for the “packaging box.”

A plugin is a folder, and the spec is quite rigid about its contents:

• plugin.json: the ID card (the only two required fields are $schema and name)
• skills/: skills, one folder per skill, containing SKILL.md (an instruction manual teaching AI how to do something)
• mcp.json: declares which MCP servers to connect to (AI’s external connections)

Previously every company’s box looked different, so the same skill had to be packaged six times. Now you package it once and all six clients can consume it. In plain terms for the average person: from now on, when you see someone on a forum say “this plugin is amazing,” you won’t have to first ask, “but I’m not using that platform, does it even work for me?”

3. How much does it cost? The free tier actually works

Per GitHub’s official plans page (read directly by this site on 2026-08-14):

Price verification date: 2026-08-14 (read directly from github.com/features/copilot/plans and the docs.github.com plans page; NT$ figures estimated at 1 USD ≈ NT$32.1, exchange rate fluctuates daily)

One thing worth flagging here that this site has stumbled into six times before: the figures above are all monthly list prices—as of this site’s check, neither of GitHub’s two official pages listed an annual price, so there’s no “annual-average-monthly-price disguised as a monthly fee” issue this time. But at the same time, the Cursor entry in this site’s tool database (that entry’s last_verified: 2026-08-14) records roughly a 20% discount for annual billing across its plans—when you see another company print a discounted monthly-average price larger than its own monthly list price, always check which type of pricing you’re looking at first.

(Cursor’s on-site listed prices, same entry, last_verified 2026-08-14: Pro US$20/month, Pro+ US$60/month, Ultra US$200/month, Teams US$40/seat/month, all billed monthly.)

4. This site’s fact-check: three things the official press releases didn’t highlight

1. The standard only governs the “box,” not “how it gets installed on your machine”

The spec’s official site, agent-plugins.org, states clearly: “Client-managed installation, distribution, enablement, updates, and user interface are outside the portable specification.”

So “build once, run everywhere” is true, but installation steps still differ by platform: Copilot CLI uses copilot plugin install, while VS Code requires searching @agentPlugins in the extensions panel. Don’t expect true one-click-for-all.

2. Anthropic isn’t on the list—the difference comes down to the outermost shell

The SKILL.md format was released by Anthropic as Agent Skills on 2025-10-16; MCP was also open-sourced by Anthropic. Both core pieces this standard packages belong to Anthropic, yet it’s neither a Core Maintainer, nor is Claude Code on the list of supported clients on launch day.

This site read Claude Code’s official documentation directly (code.claude.com/docs/en/plugins, verified 2026-08-14), and the difference comes down to specific file names:

See it now? The skills inside are the same file—what doesn’t carry over is the outer shell. Incidentally, this site also read VS Code’s official plugin documentation page, and the directory example there also writes .mcp.json (with a dot), differing from the spec’s mcp.json—this point is based on a single source only, not cross-verified; please defer to each company’s official documentation before implementation.

3. This is something that runs code on your machine

GitHub’s own Awesome Copilot learning page states, verbatim: “plugins run code on your machine, so inspect unfamiliar plugins before installing.”

The plugin marketplace can be any Git repository. The flip side of “open” is “anyone can publish.”

5. What we couldn’t verify, stated honestly

• The official compatibility list page couldn’t be scraped for content: The compatibility table at agent-plugins.org/compatible-clients loads dynamically; this site’s two attempts to fetch it on 2026-08-14 both returned only empty component tags, so we couldn’t verify each vendor’s level of support field by field.
• Cursor’s own announcement: On the date of this check, this site read Cursor’s official changelog and found no standalone announcement under the name “Agent Plugins 1.0” (8/3 had a Google Workspace “plugins” entry, and 7/28 mentioned plugins/MCP/hooks/skills under the Start plan). Cursor’s support is currently sourced from Vercel’s official list and third-party reporting, not Cursor’s own changelog.
• Codex CLI version numbers: The claim that v0.146.0 (7/29) and v0.147.0 (8/7) added Agent Plugins support comes from a third-party release-aggregation site, not from OpenAI’s official site; this site is merely relaying the information—defer to official announcements.

6. The following is Ask Cat editorial opinion, not news fact

The real news isn’t “one more standard”—it’s “five competitors willing to sit at the same table.” If Vercel’s line, “No single company’s product roadmap sets the format’s direction,” actually holds up, that’s a genuine win for users—your configurations are finally no longer hostage to one company.

But don’t mistake “open standard” for “already universally supported.” The spec itself says installation and UI are out of scope, and in practice you’ll still run into “this platform has it, that one doesn’t yet.”

Amo (the one who spots the traps): “The inventors of Skills and MCP didn’t get a seat on the committee—I don’t think I need to spell out who set this table.” Pimi (the one who finds the upside): “But the free tier is US$0 and it already works—that’s rare in the AI world.”

Both are right. The standards fight is a big-company matter; all you need to remember is: skills written into SKILL.md are a portable asset—the outer shell belongs to whoever’s turf it’s on, and that can change anytime.

7. Three things you can do today

1. You don’t need to pay to try it. GitHub Copilot Free (US$0, verified 2026-08-14) already lets you install plugins—search @agentPlugins in the VS Code extensions panel to see them.
2. Glance at the source before installing. GitHub itself says plugins run code on your machine—don’t install ones from unknown sources.
3. If you’re writing your own skills, put the content in SKILL.md, not tied to any one company’s directory structure. When you switch platforms, all you’ll need to move is the outermost config file.

Sources

Official (read directly by this site on 2026-08-14, one by one)

• Vercel official blog, “Introducing Agent Plugins” (2026-08-06, launch-day supported client list, steering committee, governance quote): https://vercel.com/blog/introducing-agent-plugins | verified 2026-08-14
• Google official developer blog, “Agent Plugins package your skills, tools, and more” (2026-08-06, Google joins as Core Maintainer): https://developers.googleblog.com/agent-plugins-package-your-skills-tools-and-more/ | verified 2026-08-14
• Agent Plugins official website (spec positioning, installation/UI out-of-scope quote): https://agent-plugins.org/ | https://agent-plugins.org/plugin-authors | verified 2026-08-14
• Agent Plugins 1.0.0 full spec text (plugin.json required fields, mcp.json path, directory examples): https://github.com/agentplugins/agent-plugins-spec/blob/main/spec/1.0.0.md | verified 2026-08-14
• GitHub official changelog, “Agent Plugins 1.0 in VS Code, Copilot CLI, and the Copilot app” (2026-08-12, “on all Copilot plans” quote): https://github.blog/changelog/2026-08-12-agent-plugins-1-0-in-vs-code-copilot-cli-and-the-copilot-app/ | verified 2026-08-14
• GitHub Copilot official plans page (US$0/US$10/US$39/US$100/US$19/US$39 monthly list prices): https://github.com/features/copilot/plans | https://docs.github.com/en/copilot/get-started/plans | price verified 2026-08-14
• GitHub Docs, “About GitHub Copilot plugins” (installation method, marketplace mechanism): https://docs.github.com/en/copilot/concepts/agents/about-plugins | verified 2026-08-14
• Awesome GitHub Copilot learning page (“plugins run code on your machine” quote): https://awesome-copilot.github.com/learning-hub/installing-and-using-plugins/ | verified 2026-08-14
• VS Code official docs, “Agent plugins” (installation method and directory example): https://code.visualstudio.com/docs/agent-customization/agent-plugins | verified 2026-08-14
• Claude Code official docs, “Create plugins” (.claude-plugin/plugin.json, .mcp.json directory table): https://code.claude.com/docs/en/plugins | verified 2026-08-14
• Claude official blog, “Agent Skills” (released 2025-10-16, SKILL.md, publicly released as an open standard): https://claude.com/blog/skills | verified 2026-08-14
• MCP official docs (“USB-C port for AI applications” quote): https://modelcontextprotocol.io/ | verified 2026-08-14
• Cursor official changelog (no standalone Agent Plugins 1.0 announcement found as of check date): https://cursor.com/changelog | verified 2026-08-14

Secondary sources (disclosed per this site’s Section 9.7)

• Codex CLI v0.146.0/v0.147.0 version info regarding Agent Plugins addition: https://releasebot.io/updates/openai/codex | verified 2026-08-14
  • This point is not sourced from OpenAI’s official website; it is cited from the third-party release-aggregation site above. This site is merely relaying the information—defer to official announcements.
• Exchange rate (1 USD ≈ 32.1 TWD, 2026-08-14): https://www.xe.com/en-us/currencyconverter/convert/?Amount=1&From=USD&To=TWD | verified 2026-08-14
  • The exchange rate is not sourced from GitHub’s official pricing page; the NT$ conversion is this site’s own estimate. GitHub prices in USD—actual charges depend on your payment method’s exchange rate.

On-site data

• This site’s tool database, github-copilot entry: last_verified 2026-08-14
• This site’s tool database, cursor entry (Pro US$20/Pro+ US$60/Ultra US$200/Teams US$40 per seat, all monthly; approx. 20% discount for annual billing): last_verified 2026-08-14

Cross-verification status (disclosed per this site’s Sections 9.1/9.2)

• “Released 2026-08-06, Core Maintainers are AWS/Cursor/Microsoft/OpenAI/Vercel, Google joined the same day”—confirmed by cross-referencing three independent official sources: Vercel’s official blog, Google’s official developer blog, and the agent-plugins.org official website.
• “GitHub Copilot supports all plans”—currently only stated explicitly by a single official source, GitHub’s official changelog, with the wording “on all Copilot plans”; GitHub Docs’ plugin concepts page does not itemize applicable plans, so this point is listed as coming from a single official source—defer to the official announcement.
• “Claude Code’s shell format differs from the spec”—confirmed by item-by-item comparison of two official documents: the Agent Plugins 1.0 spec and Claude Code’s official docs. Only two sources support this; no third-party field-by-field comparison report was found.