Package a plugin

A plugin packages your skills and the connection to your MCP server. Flow generates Claude Code and portable Agent Plugins packages from the same agent/skills/ folder.

Choose a host

Claude Code

Generate the Claude package and load it locally.

ChatGPT

Connect your server and prepare a plugin for ChatGPT.

Codex

Package your tools and workflow skills for Codex.

Other Agent Plugins hosts

Use the portable format in a compatible host.

Before you start

You need an MCP server, a URL the host can reach, and any skills in agent/skills/. The packages connect to your running server; generating them does not deploy it.

Generate and check the packages

Write the plugin output

Run this in the agent’s folder, replacing the example URL with your server’s URL:

Terminal

npx @flow-engineer/flow plugin \
  --server https://agent.example.com/mcp \
  --out plugins

Add --name my-product to choose a plugin name instead of the package name.

Validate it

Terminal

npx @flow-engineer/flow check --plugin plugins

Check it worked: both package folders exist and the check reports no stale or unsupported skill references.

Load it in your host

Choose the package format your host supports and follow that host’s installation flow. Try a request that uses one of your skills and tools.

Check it worked: the host loads the skill once and calls a tool through /mcp/plugin. Directory publication, where available, has its own submission and review process.

Generated files

Claude Code

plugins/claude/

.claude-plugin/
  plugin.json
.mcp.json
skills/
  <name>/SKILL.md

The MCP connection uses type: "http" and points to /mcp/plugin.

Agent Plugins

plugins/agent-plugins/

plugin.json
mcp.json
skills/
  <name>/SKILL.md

This uses Agent Plugins 1.0.0 and type: "streamable-http". ChatGPT and Codex accept the portable format; installation and distribution depend on the host.

Why two MCP endpoints?

Endpoint	What it delivers	Use it with
/mcp	Tools, skill descriptions and read_skill	A standalone MCP connection
/mcp/plugin	Tools only	A plugin that already ships the skill files

Both use the same tools, authentication and descriptor overrides. This gives the host one copy of each skill.

Change the plugin endpoint

Disable it with mcpServer({ ..., plugin: false }), or change it with plugin: { path: "/native" }. handle.plugin exposes its path and descriptors.

For a custom route, pass its URL ending in /plugin to the generator or update the generated MCP configuration. The server’s instructions override and extend handlers apply to both paths.

Keep it in sync

Regenerate after changing a skill or one of its assets. check --plugin compares content hashes, so checking out a file cannot make a stale package look current.

Generated manifests and copied skills are rewritten on regeneration. Keep hand-written skills outside those generated source paths. You can customize the packages and add other components alongside them. No bearer token is written into either package.

Format references: Agent Plugins 1.0.0, OpenAI plugin packaging, and Claude Code plugins. The generator’s formats were checked on 18 October 2026.

Write portable skills

Keep the workflow in one source folder.

Trace tool calls

Inspect MCP, plugin and CLI calls from the same server.