Agent Plugins

Agent Plugins

Mini-A can consume Agent Plugins 1.0.0: a portable directory format that packages skills and MCP servers together. Mini-A treats a loaded plugin as additional skill roots and ordinary MCP connections, so there is no separate plugin runtime to learn.

Plugin layout

Each plugin has a required plugin.json manifest and may include skills/ and mcp.json:

my-plugin/
├── plugin.json
├── skills/
│   └── my-skill/
│       └── SKILL.md
└── mcp.json

plugin.json must include the 1.0 schema URL and a plugin name:

{
  "$schema": "https://agent-plugins.org/schemas/1.0.0/plugin.schema.json",
  "name": "my-plugin",
  "version": "1.0.0"
}

Loading plugins

Use explicit directories with plugins=, or point Mini-A at a root that contains one level of plugin directories:

# Load named plugin directories
mini-a goal="use the available plugin skills" \
  plugins="~/plugins/reports,~/plugins/issue-tracker"

# Discover every plugin directly under this root
mini-a goal="summarize this repository" pluginsroot=~/team-plugins

pluginsroots= accepts additional comma-separated roots. Without an explicit root, Mini-A discovers plugins in ~/.openaf-mini-a/plugins (adjusted by homedir=).

Plugins compose with extraskills and mcp=. Their skill directories load after built-in and extra skill directories, so a plugin cannot shadow an existing skill name.

MCP servers

An optional mcp.json declares named servers. Mini-A supports stdio, streamable-http, and deprecated sse transports.

{
  "$schema": "https://agent-plugins.org/schemas/1.0.0/mcp.schema.json",
  "mcpServers": {
    "my-server": {
      "type": "stdio",
      "command": "./server.sh",
      "args": ["${PLUGIN_ROOT}/data"],
      "env": { "MODE": "prod" },
      "cwd": "${PLUGIN_DATA}"
    }
  }
}

For every plugin stdio server, Mini-A sets PLUGIN_ROOT (the canonical plugin directory) and PLUGIN_DATA (a managed persistent directory at ~/.openaf-mini-a/plugin-data/<plugin-name>/). Only these placeholders are expanded in arguments, environment values, and cwd. A working directory must stay within one of these boundaries; ./ paths are plugin-root-relative. Commands must be a bare executable name or a ./-relative executable, with arguments declared separately.

Remote plugin servers must use HTTPS, except for localhost HTTP. At present, only an Authorization: Bearer <token> header is passed through; other custom headers are dropped with a warning.

Compatibility and failures

Full stdio cwd and environment support requires an OpenAF runtime with native MCP pwd/envs support. Older runtimes still launch servers, but ignore those two settings.

Mini-A isolates plugin failures: an invalid manifest skips only that plugin; an invalid mcp.json leaves its skills usable; and an invalid server entry skips only that server. Warnings are logged so a broken extension does not prevent the rest of the agent configuration from starting.