Each agent ecosystem ships its own plugins / skills / extensions. This points you at each one's native mechanism. Commands and marketplaces change often and differ by agent version — VERIFY against the agent's current docs before running; never fabricate a command for an agent not listed. Announce each install; you can't restart yourself, so ask the user to restart for new extensions to take effect.
| Agent | First-party extension mechanism |
|---|---|
| Claude Code | Plugin marketplaces: /plugin marketplace add <owner>/<repo> then /plugin install <name>@<marketplace>; plus Anthropic skills (github.com/anthropics/skills) |
| Codex | /plugins — search & install in-app |
| Cursor | Rules (.cursor/rules/*.mdc), .cursor/mcp.json, and Cursor's extension/MCP marketplace |
| Gemini CLI | gemini extensions install <git-url> · gemini extensions list |
| opencode | plugins under ~/.config/opencode/plugins/ (+ its plugin docs) |
| Antigravity / Kimi / Qoder | follow each tool's current plugin/skill docs — some have no marketplace yet |
- Don't install marketplace plugins without announcing the command first.
- Don't assume an extension mechanism exists for an agent that isn't listed — check its docs.
- Don't duplicate what agent-primer already wired (the 3 core policies + any
--withbundles).