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Agent Plugins Explained: The plugin.json Packaging Standard

Reference · updated 2026-08-21 · Markdown variant

How the Agent Plugins Specification v1.0.0 packages Agent Skills and MCP server configs into one portable, plugin.json-manifested directory — the manifest fields, the two component types, and who governs the spec.

The Agent Plugins Specification is an open, vendor-neutral packaging standard that bundles Agent Skills and MCP server configurations into a single, portable directory, described by a plugin.json manifest at its root. Version 1.0.0 is the current published spec; multiple outlets place its announcement around August 6, 2026 (see Verified sources for that caveat).

Key facts

• plugin.json requires exactly two fields: $schema and name. Optional fields are version, description, author, homepage, repository, license, keywords, and extensions.
• A plugin bundles exactly two component types: skills — one or more skills/<name>/ directories, each containing a SKILL.md per the separate Agent Skills specification (see /resources/agent-skills-explained) — and MCP servers — declared in an mcp.json file, supporting stdio, streamable-http, and sse transports (see /resources/mcp-primitives).
• An optional, advanced feature lets a plugin ship client-specific behavior in reverse-domain-named directories (e.g. {namespace}/), for host-specific extensions outside the two core component types.
• The spec text is published in the agent-plugins-spec GitHub repository, alongside sibling repos agent-plugins-site and agent-plugins-example, and its own GOVERNANCE.md.

Governance

• Maintained by five named Core Maintainers, each affiliated with a different major agent-tooling vendor: Clare Liguori (Amazon), Roshan Sadanani (Cursor), Harald Kirschner (Microsoft), Gav Verma (OpenAI), and Jonathan Hefner (Vercel), who serves as Lead Core Maintainer. Google is not among the named maintainers as of this writing.
• The repo also publishes a separate, in-progress spec/1.1.0.md (marked Status: Working Draft) alongside a non-normative FUTURE_CONSIDERATIONS.md listing candidate future areas (permissions, provenance, secrets handling, etc.); v1.1.0 is not released, and this page describes only the published v1.0.0.

How this relates to Agent Skills and MCP

Agent Plugins is a packaging and distribution layer, not a replacement for either spec it bundles. It does not redefine how a Skill's SKILL.md works (see /resources/agent-skills-explained) or how an MCP server exposes tools (see /resources/building-mcp-servers) — it standardizes how a bundle of one or more skills and MCP servers ships as a single, portable, versioned directory that any compliant host can install.

Verified sources

• Agent Plugins Specification v1.0.0 (fetched directly): https://raw.githubusercontent.com/agentplugins/agent-plugins-spec/main/spec/1.0.0.md
• Core Maintainers list, MAINTAINERS.md (fetched directly, confirms Google absent): https://github.com/agentplugins/agent-plugins-spec/blob/main/MAINTAINERS.md
• Spec repository, confirming sibling repos and the v1.1.0 roadmap draft (fetched directly): https://github.com/agentplugins/agent-plugins-spec
• Announcement date (~Aug 6, 2026) and day-one integration into VS Code, GitHub Copilot, Cursor, and ChatGPT/Kiro: WebSearch-corroborated only (6 independently agreeing sources: 9to5Mac, eesel AI, explainx.ai, BigGo Finance, Codex Knowledge Base, TheNextWeb); not independently fetched — openai.com and agent-plugins.org both blocked in this sandbox.
• See also: /resources/agent-skills-explained, /resources/mcp-primitives, /resources/building-mcp-servers.

#agent-plugins #plugin-json #standard #agent-skills #mcp #packaging #agents

Category: Reference